Inorganic compound particle and process for preparation thereof

ABSTRACT

Inorganic compound particles constituted of a shell, a porous matter or a cavity enclosed therein, and the porous matter or the cavity being kept unchanged in a subsequently formed transparent coating film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/275,834, filed Nov. 8, 2002, now U.S. Pat. No. 6,777,069 entitled“Transparent Film-Coated Substrate, Coating Liquid For Transparent FilmFormation, and Display Device”, which is the national phase ofPCT/JP01/05255, filed Jun. 20, 2001, corresponding to JapaneseApplication No. 2000-185271 filed Jun. 20, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate coated with a transparentfilm, a coating liquid for forming the transparent film, and a displaydevice employing the substrate coated with the transparent film. Morespecifically, the present invention relates to a substrate coated with atransparent film, which has high strength, and is excellent inantireflection property, anti-static property, electromagneticwave-shielding property, durability, water-resistance, chemicalresistance, and in particular excellent in scratch resistance. Thepresent invention relates also to a coating liquid suitable for thetransparent film formation, and a display device having a front faceplate constructed of the substrate coated with the transparent film.

2. Description of the Prior Art

For prevention of reflection at the surface of a substrate such as aglass plate, and a plastic sheet, an antireflection film is formedthereon. For example, a film of a low-reflectance material such asmagnesium fluoride is formed on the glass or plastic sheet by vapordeposition, CVD, or a like method. However, such methods are costly.

In another method of formation of antireflection film, a coating liquidcontaining fine silica particles is applied on a glass surface to form afilm with uniform surface roughness originated from fine silicaparticles. This method intends to prevent reflection of light byreducing normal reflection by making the reflection irregular on theirregular surface formed by fine silica particles, or this methodintends to prevent reflection of light by an air layer in interspacebetween the fine particles. However, with this method, it is not easy tofix the particles onto the substrate surface or to form a single layerfilm thereof on the surface of the substrate and to control the surfacereflectance.

For further improvement, the applicant of the present inventiondiscloses use of a transparent coating film constituted of a compositeoxide particles in which porous core particle coated with silica and amatrix. This transparent film has a low reflectance, and useful as asurface coat constituent for low reflectance of a substrate such as lowreflectance glass and a low reflectance sheet or film (Japanese PatentPublication No. 7-133105).

Furthermore, in JPA 10-40834, it is described that the cathode ray tubehas a layer containing mainly SiO₂ as well as silicon materials and/orZrO₂ provided on a conductive layer containing conductive particles suchas silver. It is also described that a coating layer containing mainlySiO₂ as well as alkoxysilane containing the fluoroalkyl group is formedon the conductive particulate layer and the upper and lower coatinglayers are fired at the same time, in JPA 10-40834. By usingalkoxysilane containing fluoroalkyl groups, the water tightness andchemical resistance of the film are enhanced to provide a cathode raytube with a reflection preventing film which are effective in preventingAEF (alternating electric field) with high brightness and low surfaceresistance in JPA 10-40834.

The aforementioned transparent films, however, are not sufficient inscratch resistance, being liable to be scratched at the surface tobecome inferior in the transparency or the antireflection property ofsubstrate.

The transparent substrate for the display panel of a cathode ray tube, afluorescent display tube, or a liquid crystal display is conventionallycoated with an anti-static film for prevention of electrification of thetransparent substrate surface. The surface of this anti-static coatingfilm may further be coated with the transparent film.

As the anti-static coating film, for example, the film having a surfaceresistance of about 10² to 10¹⁰ Ω/□ is known.

As an aside, it is known that the display devices like a cathode raytube emit an electromagnetic wave. Therefore, it is known that anelectroconductive film having a low surface resistance of about 10² to10⁴ Ω/□ is formed on the surface of the display panel of the cathode raydisplay tube or the like for shielding the electromagnetic wave and theelectromagnetic field generated by the emission thereof in addition tothe aforementioned anti-static function.

An example of the above-mentioned anti-static coating film is anelectroconductive coating film formed by application of anelectroconductive film-forming liquid containing the fine particles ofelectroconductive metal oxide such as ITO on the surface of thesubstrate. Another example of the electroconductive coating film of alow surface resistance for electromagnetic wave shielding is a coatingfilm containing fine metal particulate formed on the surface of thesubstrate by application of an electroconductive film-forming liquidcontaining fine particles of electroconductive metal like Ag.

However, in the aforementioned electroconductive coating films formed onsubstrate, the fine metal particles contained therein can be oxidized,can grow to larger particles by metal ionization, or can be corroded.Thereby, the electroconductivity or light transmittance of the coatingfilm may be decreased, which lowers the reliability of the displayapparatus. Further, the electroconductive oxide particles and fine metalparticles contained in the electroconductive coating film have highrefractivity, which causes reflection of light, disadvantageously.

The disadvantages can be overcome by additional formation of atransparent coating film having a lower refractivity on theelectroconductive film to prevent the reflection and to protect theelectroconductive film.

The conventional transparent film which is coated with anelectroconductive coating film containing the fine particles of anelectroconductive metal oxide such as ITO has a low reflectivity ofabout 1% in the center wavelength portion around 500 nm to 600 nm(bottom reflectivity) of the visible light (wavelength region: 400 nm to700 nm). However, the reflectivity is higher at the wavelength regionsnear 400 nm and near 700 nm. Therefore, the luminous reflection (averagereflectivity over the entire visible light region) should be decreasedas well as the bottom reflectivity (average reflectivity around thewavelength from 500 to 600 nm).

On the other hand, when a conventional transparent coating filmcontaining a matrix composed of silica or the like is formed on theelectroconductive film surface, the density of the electroconductivefilm is liable to become nonuniform owing to the difference in theshrinkage degree between the transparent film and the electroconductivefilm. As a consequence, failure of electrical contact between theelectroconductive fine particles may result and insufficient overallelectroconductivity of the film may develop.

Furthermore, in the heat treatment, the transparent coating film is notsufficiently densified and is porous so as to form cracks and voids,which may permit penetration of moisture and chemicals such as acids andalkalis, all of which are disadvantages.

An acid or alkali which penetrates into the transparent coating film mayreact with the surface of the substrate to lower the refractivity, ormay react with the fine particles of the metal or the like in the formedelectroconductive coating film, when it is employed, to lower thechemical resistance of the coating film and to decrease the anti-staticproperty and electromagnetic wave shielding effect of theelectroconductive film, disadvantageously.

In the case where the transparent film is formed on the surface of theelectroconductive film containing the fine metal particles, although thebottom reflectivity is as low as 0.2%, the reflectivities near 400 nmand near 700 nm are high, and the luminous reflectivity is in the rangeof about 0.5 to 1%. This makes the visual feeling of the imagereflection (mirror reflection) stronger, and the coloration of thereflected light cannot readily be suppressed. Therefore, the transparentfilm should further be improved in the anti-reflection property.

The inventors of the present invention, after comprehensiveinvestigation on the low reflectivity film to be formed on theelectroconductive coating film, found a transparent film comprising amatrix containing a silicone having a fluorine-substituted alkyl group,and an inorganic compound particles constituted of a shell and a porousmatter or cavity enclosed therein. This transparent coating film has asufficiently low refractive index, a low shrinkage property, andhydorphobicity, and adheres well to the substrate and the transparentelectroconductive layer, having high film strength and high scratchresistance. The substrate coated with such a transparent film isexcellent in durability, water resistance, chemical resistance, andanti-reflection. The transparent film formed on the electroconductivefilm surface gives excellent anti-static property and excellent luminousreflection factor, preventing the mirror reflection, and the colorationof the reflection. Thereby, a display device can be made which hasexcellent display performance. Thus the present invention has beenachieved.

SUMMARY OF THE INVENTION

The present invention intends to provide a substrate coated with atransparent coating film, containing specified inorganic compoundparticles and a specified fluorine-containing silicone, which has lowreflectivity, low shrinkage property, and high hydrophobicity, and whichis excellent in adhesiveness to the substrate or the transparentelectroconductive layer (transparent electroconductive coating film)when the layer is formed, film strength, chemical resistance, and likeproperties. The present invention intends also to provide a coatingliquid suitable for formation of the above transparent film, and adisplay device employing the transparent film coated substrate beingexcellent in anti-static properties and electromagnetic wave shieldingproperties.

An embodiment of the transparent film-coated substrate comprises asubstrate and a transparent coating film formed thereon wherein thetransparent coating film comprises (i) a matrix containing a siliconehaving a fluorine-substituted alkyl group and (ii) inorganic compoundparticles constituted of a shell, and a porous matter or a cavityenclosed therein, the porous matter or the cavity is kept unchanged inthe formed transparent coating film.

Another embodiment of the transparent film-coated substrate is comprisedof a substrate, an electroconductive layer formed on the surface of thesubstrate, and a transparent coating film formed on the surface of theelectroconductive layer.

Wherein the transparent coating film comprises (i) a matrix containing asilicone having a fluorine-substituted alkyl group, and (ii) inorganiccompound particles constituted of a shell and a porous matter or acavity enclosed therein, the porous matter or the cavity is keptunchanged in the formed transparent coating film.

The display device of the present invention has a front face plateconstituted of the aforementioned transparent film-coated substrate inwhich the transparent film is placed outside the front face plate.

The cathode ray tube of the present invention has a front face plate(panel) constituted of the aforementioned transparent film-coatedsubstrate in which the transparent film is placed outside the front faceplate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are schematic sectional views of the inorganic particleconstituted of a shell, and porous matter or cavity enclosed therein.

FIG. 2 is a TEM photograph of a cross-section of the inorganic particles(having a cavity enclosed by the shell).

FIG. 3 is a TEM photograph of a cross-section of the transparent filmcontaining the inorganic particle (having a cavity enclosed by theshell).

FIG. 4 is a reflectivity curve in the wavelength region 400 to 700 nmmeasured by Example 13.

DETAILED DESCRIPTION OF THE INVENTION

The transparent film-coated substrate is comprised of a substrate, and atransparent coating film formed on the surface of the substrate, orcomprised of a substrate, an electroconductive layer formed on thesurface of the substrate, and a transparent coating film formed on thesurface of the electroconductive layer surface.

Substrate

The substrate employed in the present invention includes flat platescomposed of glass, plastics, metal, ceramics, or the like, as moldedarticles shape of the substrate, such as films, sheet, and the like areexemplified, molds such as glass, bottles, PET bottles, glass plates maybe used as the substrate.

In the present invention, an electroconductive layer described below maybe provided on the surface of the substrate.

Electroconductive Layer

The electroconductive layer may be formed from any knownelectroconductive material without special limitation, provided that ithas a surface resistance of not higher than 10¹² Ω/□. Theelectroconductive layer has preferably a thickness ranging from 5 to 200nm, more preferably from 10 to 150 nm. Within this layer thickness, thetransparent film coated substrate has excellent electromagneticwave-shielding property and excellent anti-static property. (□ meansthat the specimen used for surface resistance is a quadrangle such as 1cm square.)

For the anti-static property, the electroconductive layer is formed tohave a surface resistance ranging from 10⁴ to 10¹² Ω/□. For theelectromagnetic field shielding property, the electroconductive layer isformed to have a lower surface resistance ranging from 10² to 10⁴ Ω/□.In the case where a transparent coating film is formed on theelectroconductive layer, the surface resistance of the electroconductivelayer is not substantially changed. The electroconductive layer may beformed in two or more layers.

The transparent electoroconductive material includes inorganicelectroconductive material such as metals, electroconductive inorganicoxides, and electroconductive carbon; electroconductive polymers such aspolyacetylene, polypyrrole, polythiophene, polyaniline,polyisothianaphthene, polyazulene, polyphenylene, poly-p-phenylene,poly-p-phenylene-vinylene, poly-2,5-thienylenevinylene, polyasen, andpolyperinaphthalene.

The above electroconductive polymers may be doped with dopant ions ifnecessary.

Of the above materials, preferred are inorganic electroconductivematerials including metals, electroconductive inorganic compounds, andelectroconductive carbon. For formation of the electroconductive layerfrom the above electroconductive material, a fine particulate metal(fine particles of a metal), or a fine particulate inorganic oxide (fineparticles of an electroconductive inorganic oxide) is used (hereinafter,these particles may be merely referred to as electroconductive particlesin the specification).

The known fine metal particles can be used with no limitation. The metalfilm particles may be composed of a single component, or composed ofcomposite metal particles containing two or more metal components.

The two or more metals constituting the fine composite metal particlesmay be an alloy in a solid solution state, or an eutectic mixture not ina solid solution state, or an alloy and an eutectic mixture coexisting.The fine composite metal particles are retarded particle growth becauseof less liability of oxidation or ionization of the metal, and have highcorrosion resistance. Therefore the fine particles have high reliabilitysuch as less drop of electroconductivity or light transmittance.

The fine metal particles are selected from the group consisting of Au,Ag, Pd, Pt, Rh, Ru, Cu, Fe, Ni, Co, Sn, Ti, In, Al, Ta, and Sb. Themetals for the composite metal particulates are two or more selectedfrom the group consisting of Au, Ag, Pd, Pt, Rh, Ru, Cu, Fe, Ni, Co, Sn,Ti, In, Al, Ta, and Sb. The preferred combination of two or more metalsincludes Au—Cu, Ag—Pt, Ag—Pd, Au—Pd, Au—Rh, Pt—Pd, Pt—Rh, Fe—Ni, Ni—Pd,Fe—Co, Cu—Co, Ru—Ag, Au—Cu—Ag, Ag—Cu—Pt, Ag—Cu—Pd, Ag—Au—Pd, Au—Rh—Pd,Ag—Pt—Pd, Ag—Pt—Rh, Fe—Ni—Pd, Fe—Co—Pd, and Cu—Co—Pd.

When the metal of fine particle is selected from the group consisting ofAu, Ag, Pd, Pt, Rh, Cu, Co, Sn, In, and Ta, a portion of the metal maybe in an oxidized state, or the metal may contain an oxide of the metal.Further, a P atom or B atom may be contained by linkage.

Such a fine metal particle can be prepared by a known process, forexample as shown below (see Japanese Patent Application Laid-Open No.10-188681).

(i) A metal salt or two or more metal salts are reduced separately orsimultaneously in an alcohol-water mixed solvent. In this process, areducing agent may be added if necessary. The reducing agent includesferrous sulfate, trisodium citrate, tartaric acid, sodium borohydrate,and sodium hypophosphite. The reduction may be conducted by heating at atemperature higher than about 100. in a pressure vessel.

(ii) Into a dispersion of a fine metal particle of a single component ora fine alloy particle, another fine particle or ion of a metal having astandard hydrogen electrode potential higher than that of theaforementioned metal or alloy is added to deposit the metal of a higherstandard hydrogen electrode potential onto the fine metal particleand/or the fine particles. In this process, a metal having a stillhigher standard hydrogen electrode potential may be deposited furtheronto the above prepared fine composite metal particle. The metal havingthe highest standard hydrogen electrode potential exists preferably in alarger amount in the surface layer of the composite metal particles. Themetal of the highest standard hydrogen electrode potential existing in alarger amount on the surface layer of the fine composite metal particlesretard oxidation and ionization of the fine composite metal particles,and will retard the growth caused by ion migration or a like phenomenon.Further, the use of such fine composite metal particles leads the dropof electroconductivity and of light transmittance to retard because thefine composite metal particles have higher corrosion resistance.

The metal particulate has an average particle diameter ranging from 1 to200 nm, preferably from 2 to 70 nm. Within this particle diameter range,the formed electroconductive layer is transparent. The metal particulatehaving an average particle diameter larger than 200 nm absorbs morelight to lower the light transmittance of the particle layer and toincrease the haze. Therefore, such a film-coated substrate used, forexample, as a front face plate of a cathode ray tube can lower theresolution of the displayed image. On the other hand, the fine metalparticles having the average particle diameter of less than 1 nm tend toincrease the surface resistance of the particulate layer greatly, whichmay make it difficult to achieve the object of the present invention.

The applicable electroconductive inorganic particulate may be any knownfine transparent electroconductive inorganic particles or particulatecarbon.

The fine electroconductive inorganic oxide particles includes tin oxide;doped tin oxide doped with Sb, F, or P; indium oxide; doped indium oxidedoped with Sn or F; antimony oxide, and titanium lower order oxide.

The electroconductive inorganic particulate has an average particlediameter ranging from 1 to 200 nm, preferably from 2 to 150 nm.

The electroconductive layer can be formed by application of a coatingliquid for electroconductive film formation (hereinafter referred to asan electroconductive film forming liquid).

The coating liquid contains the aforementioned fine electroconductiveparticles and a polar solvent.

The polar solvent for the electroconductive film forming liquid includeswater; alcohols such as methanol, ethanol, propanol, butanol, diacetonealcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol,and hexylene glycol; esters such as methyl acetate, and ethyl acetate;ethers such as diethyl ether, ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, ethylene glycol monobutyl ether, diethyleneglycol monomethyl ether, and diethylene glycol monoethyl ether; ketonessuch as acetone, methyl ethyl ketone, acetylacetone, and acetoacetateesters. These solvents may be used singly or in combination of two ormore thereof.

By use of a coating liquid containing the fine metal particles, atransparent electroconductive layer can be formed which has a surfaceresistance ranging from about 10² to about 10⁴ Ω/□, giving theelectromagnetic wave-shielding effect. For formation of theelectroconductive layer for electromagnetic wave-shielding by use of thefine metal particles, the electroconductive film-forming liquid containsthe fine metal particle at a concentration ranging preferably from 0.05%to 5% by weight, more preferably from 0.1% to 2% by weight.

The electroconductive film-forming liquid containing the fine metalparticles at a concentration lower then 0.05% by weight tends to give asmaller thickness of the produced film resulting in insufficientelectroconductivity of the film. On the other hand, at a fine metalparticles concentration of higher than 5% by weight, the coating liquidtends to produce a larger thickness of the film to lower the lighttransmittance to deteriorate the transparency and impair the appearanceof the layer.

The electroconductive film-forming liquid may contain the aforementionedelectroconductive inorganic particles in addition to the fine metalparticles. To obtain a transparent electroconductive layer having asurface resistance ranging from 10² to 10⁴ Ω/□ for the electromagneticwave shielding effect, the electroconductive inorganic particles may becontained in an amount of not more than 4 parts by weight based on onepart of the fine metal particle. With the electroconductive inorganicparticles contained in an amount of more than 4 parts by weight, theelectroconductivity may be lower not to give sufficient electromagneticwave shielding effect undesirably because the portion of the fine metalparticles in electroconductive film is decreased.

The coating liquid containing both the fine metal particles and the fineelectroconductive inorganic particles can produce a transparentelectroconductive particulate layer having higher transmittance than thelayer formed from the fine metal particle only. The incorporation of thefine electroconductive inorganic particle and the fine metal particleenable transparent electroconductive layer formation at a lower cost.

For formation of the electroconductive layer having the surfaceresistance ranging from about 10⁴ to 10¹² Ω/□ for anti-static property,the electroconductive film-forming liquid may contain only the fineelectroconductive particle. The electroconductive film-forming liquidcontains the electroconductive inorganic particle at a concentrationranging preferably from 0.1% to 1% by weight, more preferably from 0.5%to 5% by weight. At the concentration of lower than 0.1% by weight ofthe fine electroconductive particles, the resulting film tends to bethinner, which may give insufficient anti-static property. On the otherhand, at the concentration of higher than 10% by weight of the fineelectroconductive particles, the resulting film tends to be thicker tolower the light transmittance to decrease the transparency and impairthe appearance of the film.

The electroconductive film-forming liquid may further contain a dye or apigment to uniformly transmit visible light throughout the visible lightwavelength range.

The solid content (the total amount of the fine metal particles, and/orthe fine electroconductive particles except for the fine metal particle,and an optionally added additive such as a dye and a pigment) in thecoating liquid is preferably not higher than 15% by weight, morepreferably in the range from 0.15% to 5% by weight in view of thefluidity of the liquid, and the dispersibility of the fine metalparticle and other particulate components in the coating liquid.

The electroconductive film-forming liquid employed in the presentinvention may contain a component for a matrix which functions as thebinder for the fine metal particles and fine electroconductive particleexcept for the fine metal particle after the film formation. The matrixcomponent may be any known material. In the present invention, thebinder material is preferably one or more oxide precursors selected fromthe group consisting of precursors of silica, composite oxidescontaining silica component, zirconia, and antimony oxide. Particularlyhydrolysis-polycondensation products of organic silanes such asalkoxysilanes, and silicic acid prepared by dealkalization of alkalisilicate are preferable as precursors. A resin for a paint may also beuseful therefor.

The matrix component is contained in an amount ranging from 0.01 to 0.5part by weight, preferably from 0.03 to 0.3 part by weight based on onepart by weight of the fine metal particles.

For higher dispersibility of the fine electroconductive particles, theelectroconductive film-forming liquid may contain an organic stabilizer.The organic stabilizer includes specifically gelatin; polyvinyl alcohol;polyvinylpyrrolidone; polybasic carboxylic acids such as oxalic acid,malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid,maleic acid, fumaric acid, phthalic acid, and citric acid, and saltsthereof; sulfonate salts; organic sulfonate salts; phosphate salts;organic phosphate salts; and heterocyclic compounds; and mixturesthereof.

The amount of the organic stabilizer used depends on the kind of theorganic stabilizer, the diameter of the fine electroconductiveparticles, and so forth, ranging preferably from 0.005 to 0.5 part byweight, more preferably from 0.01 to 0.2 part by weight based on onepart of the particles. With the amount of less than 0.005 part byweight, the organic stabilizer tends not to give sufficientdispersibility, whereas with the amount of more than 0.5 part by weight,it may lower the electroconductivity.

Formation of Electroconductive Layer

The electroconductive layer is formed by applying the aforementionedelectroconductive film-forming liquid onto a substrate, and drying theapplied liquid.

For example, the electroconductive film-forming liquid is applied on asubstrate by dip coating, spinner coating, spray coating, roll coatercoating, flexographic printing, or a like coating method, and theapplied liquid is dried at a temperature ranging from room temperatureto about 90° C.

The electroconductive film-forming liquid which contains theaforementioned matrix component may be heat-treated after application tocure the matrix component. In the heat treatment, the dried coating filmafter the drying is heated to cure the matrix component. The heattreatment temperature is preferably not lower than 100° C., morepreferably ranges from 150° C. to 300° C. The heat treatment at atemperature lower than 100° C. does not necessarily cure the matrixcomponent sufficiently. The upper limit of the heat treatmenttemperature should be below the temperature of decomposition, melting,or burning of the substrate, depending on the kind of the substrate.

The matrix component may be cured by electromagnetic wave irradiation,treatment in an atmosphere of a cure-promoting gas, or other method inplace of the heat treatment.

Transparent Coating Film

A transparent coating film is formed on the surface of theaforementioned substrate or the aforementioned electroconductive layerin the present invention. The transparent coating film comprisesinorganic particulate and a matrix as described below.

Inorganic Compound Particle

The inorganic compound particulate employed in the present inventioncomprises a shell, and a porous matter or a cavity enclosed by theshell. The porous matter or the cavity in the inorganic particle is keptunchanged in the formed transparent film.

FIGS. 1A-1D show schematically sectional views of the inorganic compoundparticle. In FIGS. 1A-1D, the numeral 1 denotes a shell layer, thenumeral 2 denotes a porous matter, and the numeral 3 denotes a cavity.

The inorganic particle employed in the present invention may have aporous matter enclosed by the shell as shown in FIG. 1A, may have acavity as shown in FIG. 1B, or may have a porous matter partially filledand a cavity enclosed by the shell as shown in FIGS. 1C and 1D.

The cavity 3 contains a solvent (mentioned later), a gas, or a likematter employed in preparation of the inorganic compound particles.

The inorganic compound particles have an average particle diameterranging preferably from 5 to 300 nm, more preferably 10 to 200 nm. Theaverage diameter of the used inorganic compound particles is suitablyselected corresponding to the thickness of the transparent coating filmto be formed.

The thickness of the shell layer ranges preferably from 1 to 20 nm, morepreferably 2 to 15 nm. With the thickness less than 1 nm, the shelllayer does not always cover completely the particle. The incompletecoverage of the particle may permit ready penetration of afluorine-containing matrix precursor such as monomers and oligomers forforming a matrix (mentioned later) into the inorganic compound particleto decrease the porosity inside and to decrease the effect of the lowrefractivity. With the thickness more than 20 nm, the constitution ratioof the shell layer is higher to decrease the ratio of the porous matterto reduce the effect of the low refractivity, although the penetrationof the fluorine-containing matrix precursor like the fluorine-containingsilicone monomers or oligomers is prevented.

The particle being entirely cavitied inside (FIG. 1B) and having theshell layer of less than 1 nm thick may be collapsed, whereas theparticle having the shell layer of more than 20 nm thick has higherconstituting ratio of the shell layer and lower cavity volume ratio inthe particle to decrease the effect of the low refractivity.

The overall void ratio of the inorganic compound particle employed inthe present invention is preferably not less than 10% by volume. Theparticle having the interior filled with the porous matter has a voidratio ranging from 10% to 20% by volume. The particle having a cavityinside has void ratio of higher than 20% by volume, preferably higherthan 22% by column.

The shell (layer) of the inorganic compound particle is preferablyconstituted mainly of silica. The shell (layer) may contain a non-silicacomponent, which is specifically oxides selected from the group ofAl₂O₃, B₂O₃, TiO₂, ZrO₂, SnO₂, CeO₂, P₂O₅, Sb₂O₃, Sb₂O₅, MoO₃, ZnO, andWO₃.

The compound for constituting the porous matter (hereinafteroccasionally referred to a porous material) inside the shell layerincludes silica, combination of silica and other inorganic compound,CaF₂, NaF, NaAlF₆, and MgF. Of these, particularly preferred arecomposite oxides composed of silica and a non-silica inorganic oxide.The non-silica inorganic oxide is one or more of the compounds selectedfrom the group consisting of Al₂O₃, B₂O₃, TiO₂, ZrO₂, SnO₂, CeO₂, P₂O₅,Sb₂O₃, Sb₂O₅, MoO₃, ZnO, and WO₃. The compound constituting the porousmatter (porous material) contains silica (SiO₂) and the non-silicainorganic compound (in term of oxide: MO_(x)) in a molar ratioMO_(x)/SiO₂ ranging preferably from 0.0001 to 1.0, more preferably from0.0001 to 0.3. The porous material of molar ratio MO_(x)/SiO₂ Of lessthan 0.0001 cannot readily be prepared, and even if it could beobtained, it would not give lower refractive index. At the molar ratioMO_(x)/SiO₂ of higher than 1.0, the pore volume may be smaller and therefractive index may not be low because of the smaller ratio of thesilica.

The inorganic compound particle, which has a shell layer constitutedmainly of silica, in the present invention, has a refractive index ofnot higher than 1.41 preferably.

When such an inorganic compound particulate has inside a porous mattermainly constituted of silica, the refractive index thereof ranges from1.37 to 1.41, and the void ratio ranges from 10% to 20% by volume. Whenthe inside of the shell is cavitied (including the inside having aporous matter and a cavity), the refractive index is lower than 1.37,preferably lower than 1.36 and the void ratio is higher than 20% byvolume, preferably higher than 22% by volume.

The use of the specific inorganic particles having a lower refractiveindex leads to obtaining transparent film coated substrate havingespecially excellent antireflection property.

The refractive index is measured as described below. Firstly, coatingliquids for refractive index measurement are prepared by mixing an SiO₂matrix forming liquid (M) and the inorganic compound particle at weightratios of the matrix (weight in term of SiO₂) to inorganic compoundparticles (weight in term of oxides) of 100:0, 90:10, 80:20, 60:40,50:50, and 25:75. The coating liquids are applied respectively on asilicon wafer having the surface kept at 50° C. by spinner coating at300 rpm. The coated films are heat-treated at 160° C. for 30 minutes.The refractive indexes of the formed coating films for refractive indexmeasurement are measured by an ellipsometer. Then the obtainedrefractive indexes are plotted as a function of the particle mixingratio (Particle: (oxide)/[Particle:(oxide)+Matrix:SiO₂]. The plots areextrapolated to 100% particle content. This extrapolated value is takenas the refractive index of the inorganic particles.

The void volume is estimated by calculating the air volume from thedifference between the above obtained refractive index and therefractive index (1.45) of pure SiO₂ to obtain the void ratio.

The cavity inside the shell is filled partly with the solvent used inthe preparation of the particles, gas and the porous matter. The solventin the cavity may contain the unreacted particle precursor, and catalystemployed. The cavity-filling matter may be a single component, or amixture of two or more components. The inorganic compound particlecontains silica and non-silica inorganic compound (in term of oxide:MO_(x)) in a molar ratio MO_(x)/SiO₂ ranging preferably from 0.0001 to0.1, more preferably from 0.0001 to 0.3.

The aforementioned porous matter or the cavity in the shell layer of theinorganic compound particle are maintained in the formed transparentfilm as mentioned before.

FIG. 2 is a TEM photograph of a cross-section of the inorganic compoundparticles having a cavity enclosed by the shell.

The shell layer is composed of silica (thickness 1.5 nm; particlediameter 96 nm), having a refractive index of 1.31, a void ratio of 31%.The ratio of the cavity is calculated to be 32% assuming that the insideis occupied by air. Therefore, the cavities are formed obviously in theshell.

FIG. 3 is a TEM photograph of a cross-section of the inorganic compoundparticles in the transparent coating film formed from the inorganiccompound particles and the matrix explained later, the particles havinga cavity inside the shell. FIG. 3 shows clearly that the cavities areretained in the formed transparent film without penetration of thematrix component into the cavities.

Preparation of Inorganic Compound Particles

The inorganic compound particles are produced suitably, for example, bya process for producing composite oxide colloid particles disclosed inJapanese Patent Application Laid-Open No. 7-133105.

Specifically, the inorganic compound particles constituted of silica anda non-silica inorganic compound can be produced through Steps 1 to 3shown below.

Step 1: Preparation of Particles of Porous Material Precursor

In this Step 1, aqueous alkali solutions of a silica source (rawmaterial) and a non-silica inorganic compound source (raw material) areseparately prepared, or an aqueous solution of a mixture of the silicasource and the non-silica inorganic compound source is preparedpreliminarily. The aqueous solution or solutions are added gradually toan aqueous alkali solution having a pH 10 or higher with stirringcorresponding to the composite ratio of the composite oxide to formprecursor particles of the porous material (hereinafter referred to asporous material precursor particles).

The silica source includes silicate salts of alkali metals, ammonium, ororganic bases. The alkali metal silicates include sodium silicate (waterglass) and potassium silicate.

The organic base includes quaternary ammonium salts such astetraethylammonium salt: amines such as monoethanolamine,diethanolamine, and triethanolamine. The ammonium silicate and theorganic base silicates include alkaline solutions prepared by addingammonia, a quaternary ammonium hydroxide, or an amine compound to asilicic acid solution.

The source material for the non-silica inorganic compound includesalkali-soluble inorganic compound, specifically including oxo-acids ofthe element selected from Al, B, Ti, Zr, Sn, Ce, P, Sb, Mo, Zn, W and soforth; alkali metal salts, alkaline earth metal salts, ammonium salts,and quaternary ammonium salts of the oxo-acids. More specifically,preferred are sodium aluminate, sodium tetraborate, zirconylammoniumcarbonate, potassium antimonate, potassium stannate, sodiumaluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodiumphosphate.

On mixing the above aqueous source material solutions, the pH of themixed aqueous solution changes immediately. However, no control isnecessary for controlling the pH in a certain range. The pH of theresulting aqueous solution will reach finally to a certain leveldepending on the kind of inorganic oxides and the mixing ratio. Thespeed of the mixing of the aqueous solution is not specially limited.

In preparation of a porous material precursor particles for theinorganic compound particles, which has a porous composite oxide as theinside porous material, a liquid dispersion of seed particles may beused as the starting material. The seed particle includes fine particleof inorganic oxides of SiO₂, Al₂O₃, TiO₂, ZrO₂, and the like andcomposite oxides thereof. Usually a sol of the oxide may be used. Theliquid dispersion of the porous material precursor particles obtained bythe above preparation method may be used as the seed particledispersion. When the seed particle dispersion is used, the pH value ofthe seed particle dispersion is adjusted to pH 10 or higher, and theretothe aqueous solution of the aforementioned compound is added withstirring. In this operation also, the pH of the dispersion need not becontrolled. The use of the seed particles will facilitate the particlesize control of the prepared porous material precursor particles withuniformity of the particle size.

The above silica source materials and the inorganic compound sourcematerials have respectively a high solubility in alkaline region.However, in mixing of the both source materials in the pH region of highsolubility, the formed oxo-acid ions such as silicate ions and aluminateions having low solubilities will precipitate as a composite oxide togrow fine particles or precipitation thereof on the seed particles togrow in size. Therefore, in the precipitation and growth of theparticles, the pH control as conducted in the conventional process isnot necessary.

In this Step 1, the silica and the non-silica inorganic compound areused in a molar ratio (MO_(x)/SiO₂) ranging preferably from 0.05 to 2.0,more preferably from 0.2 to 2.0, where the inorganic compound iscalculated in terms of oxide (MO_(x)). Within this composite ratio, thesmaller ratio of the silica will give a larger pore volume in the porousmaterial. At an MO_(x)/SiO₂ ratio higher than 2.0, the pore volume inthe porous material tends to increase little, whereas at the MO_(x)/SiO₂ratio lower than 0.05, the pore volume tends to be smaller. Especially,in case of formation of a cavity in the inorganic shell layer, the molarratio MO_(x)/SiO₂ ratio ranges preferably from 0.25 to 2.0. At the molarratio MO_(x)/SiO₂ lower than 0.25, the cavity is not always formed inthe subsequent Step 2.

Step 2: Removal of Non-Silica Inorganic Compound from Porous MaterialPrecursor Particles

In Step 2, from the porous material precursor particles, non-silicainorganic compound (elements other than silicon and oxygen) isselectively removed at least partly. Specifically, the inorganiccompound in the porous material precursor particles is removed bydissolution by a mineral acid or an organic acid, or removed by ionexchange by contact the obtained porous material precursor particlesdispersion with a cationic ion exchange resin.

The porous material precursor particles prepared in Step 1 have anetwork structure in which silicon and an element constituting theinorganic compound are linked through oxygen. From the porous materialprecursor particles, the inorganic compound (elements other than siliconand oxygen) is removed to obtain porous particles having a higherporosity and larger pore volume. Such a porous particle constitutes theporous matter inside the shell.

The particles having a cavity inside the shell can be prepared byincreasing the amount of removal of the non-silica inorganic compoundfrom the porous matter precursor particles.

Preferably, a protecting silica film is formed on the surface of theporous material precursor particles before the removal of the non-silicainorganic compound from the porous material precursor particles. Theprotecting silica film is formed by adding a silicic acid solutionobtained by dealkalizing the alkali metal salt or a hydrolyzable organicsilicon compound to the liquid dispersion of the porous materialprecursor particles prepared in Step 1. The protecting silica film has athickness ranging preferably from 0.5 to 15 nm. This protecting silicafilm formed in this step is porous and thin, so that it does not preventthe removal of the non-silica inorganic compound from the porousmaterial precursor particles.

The formation protecting silica film leads to removal of theaforementioned non-silica inorganic compound from the particle whileretaining the particle shape of the porous material precursor particles.

Further, the formation of protecting silica film prevents, in the outershell layer formation, clogging (closing) of pores of the porousparticles by the hydrolyzable organic silicon compound or the silicicacid as the silica shell forming component, enabling formation of thesilica shell mentioned later without decreasing the pore volume.

When the amount of the inorganic compound to be removed from the porousmaterial precursor particles is small, the protection film need not beformed since the particles are not broken by the removal operation.

For preparation of particles having a cavity inside the shell, theformation of the protecting silica film is particularly preferred. Inpreparation of particles having a cavity inside the shell, the inorganiccompound is removed to leave a precursor of particle having a cavityinside the shell constituted of the protecting silica film, a solventinside the protecting silica film, and the remaining undissolved part ofthe porous material. Formation of the silica shell layer on thisparticle precursor produces the inorganic compound particle having ashell constituted of the protecting silica film and the silica shelllayer, and inorganic particles having a cavity inside.

In formation of the protecting silica film, the amount of the silicasource is preferably less, insofar as the particle shape can beretained. An excessive amount of the silica source results in anexcessive thickness of the protecting silica film, which may renderdifficult the removal of the non-silica inorganic compound from theporous material precursor particles.

The hydrolyzable organic silicon compound for formation of theprotecting silica film includes alkoxysilanes represented by generalFormula: R_(n)Si(OR′)_(4-n) where R and R′ are respectively ahydrocarbon group such as alkyl, aryl, vinyl, and acryl; n is an integerof 0, 1, 2, or 3. Of these, preferred are tetraalkoxysilanes such astetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane.

In the film formation, a mixed solution of the alkoxysilane, pure water,and an alcohol containing a small amount of an alkali or acid as thecatalyst is added to a liquid dispersion of the aforementioned porousmaterial precursor particles, whereby the alkoxysilane is hydrolyzed toform a silicic acid polymer and the formed silicic acid polymer isallowed to deposit on the surface of the porous material precursorparticles. In this operation, in place of the mixed solution, thealkoxysilane, the alcohol, and the catalyst may be concurrently added tothe porous material precursor particles dispersion. The alkali catalystincludes ammonia, alkali metal hydroxides, and amines. The acid catalystincludes inorganic acids and organic acids.

In the case where the dispersion medium of the porous material precursorparticles is water only, or contains water in a larger amount relativeto the organic solvent, the protecting silica film can be formed by useof a silicic acid solution. In this case, the silicic acid in aprescribed amount is added to the dispersion, and simultaneously analkali is added thereto to deposit the silicic acid onto the surface ofthe porous material precursor particles. The silicic acid and thealkoxysilane may be used in combination for the protecting silica filmformation.

As described above, from the porous material precursor particles, thenon-silica inorganic compound is removed to obtain a dispersion ofporous material particles or of precursor of the particles having cavityinside the shell.

Step 3: Formation of Silica Shell Layer

In Step 3, a hydrolyzable organic silicon compound or silicic acidsolution is added to the porous material particle (including theprecursor of particle having a cavity inside the shall) dispersionprepared in Step 2. Thereby, a silica shell layer is formed from apolymer of hydrolyzable organic silicon compound or a silicic acidsolution to coat the surface of the porous particles (precursorparticles for cavity formation). In the formation of silica shell, theuse of singly hydrolyzable organosilicon compound is preferable. Whensilicic acid solution is used, it is preferred to mix with hydrolyzableorganosilicon compound. The portion of silicic acid in the mixture ofsilicic acid and hydrolyzable organosilicon compound is preferably notmore than 30% by weight.

The hydrolyzable organic silicon compound for formation of the silicashell layer includes aforementioned alkoxysilanes represented by generalFormula: R_(n)Si(OR′)_(4-n) where R and R′ are respectively ahydrocarbon group such as alkyl, aryl, vinyl, and acryl; n is an integerof 0, 1, 2, or 3. Of these, preferred are tetraalkoxysilanes such astetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane.

In the shell formation, a mixed solution of the alkoxysilane, purewater, and an alcohol containing a small amount of an alkali or acid asthe catalyst is added to a liquid dispersion of the aforementionedporous material particles, whereby the alkoxysilane is hydrolyzed toform a silicic acid polymer and the formed silicic acid polymer isallowed to deposit on the surface of the porous material particles toform the shell layer. In this operation, in place of the mixed solution,the alkoxysilane, the alcohol, and the catalyst may be individuallyadded to the dispersion. The alkali catalyst includes ammonia, alkalimetal hydroxides, and amines. The acid catalyst includes inorganic acidsand organic acids.

In the case where the dispersion medium of the porous particles (theprecursor of particle having cavity inside the shell) is water only, ormixed solvent containing water in a larger amount relative to an organicsolvent, the shell layer may be formed by use of a silicic acidsolution. The silicic acid solution herein means an aqueous solution ofa low polymer of silicic acid prepared by dealkalization of aqueoussolution of an alkali metal silicate such as water glass by ionexchange.

When the silicic acid is used for the shell layer formation, the silicicacid is added to the liquid dispersion of the porous material particles(the precursor of particle having a cavity inside the shell), andsimultaneously an alkali is added thereto to deposit a low polymer ofthe silicic acid onto the surface of the porous particles to form theshell layer (hereinafter the obtainable particle is called the shelledparticle). The silicic acid and the alkoxysilane may be used incombination for the shell layer formation.

The organic silicon compound for shell layer formation is added to theporous particle dispersion in an amount to enable to coat sufficientlythe surface of the porous particles. Specifically, the organic siliconcompound for shell layer foundation is added so as to form the silicashell having the thickness in the range of 1 to 20 nm. With a protectingsilica film having been provided, the organic silicon compound or thesilicic acid is used in an amount to obtain the total thickness of theprotecting silica film and the silica shell layer ranging from 1 to 20nm.

Subsequently, the dispersion of the shelled particles is heat-treated tocompact the formed silica shell layer. The heat treatment temperature isnot limited provided that the fine pores in the silica shell layer arenot clogged, preferably ranging from 80 to 300° C. For heat treatment ata temperature higher than the boiling point, a pressure reaction vesselmay be used. The heat treatment at a temperature lower than 80° C. maycause clogging of the fine pores of the silica shell without compactingthe shell layer, or may require much time for the treatment. On theother hand, whereas the heat treatment at 300° C. or higher for a longtime may compact the inner porous material-constituting compound (porousmatter), not achieving the low refractivity undesirably.

The inorganic compound particles obtained as above have a low refractiveindex of not higher than 1.41. The porosity of the inorganic compoundparticles owing to the porous material contained inside or a cavityinside gives the low refractive index.

Matrix

The transparent coating film contains a fluorine-substitutedalkyl-containing silicone component as the matrix. Thefluorine-substituted alkyl-containing silicone component includespreferably those having the constituting unit represented by any of theformulas (1) to (3) below:

where R′ is a fluoroalkyl or perfluoroalkyl group of 1-16 carbon atoms;R² is an alkyl, halogenated alkyl, aryl, alkylaryl, arylalkyl, alkenyl,or alkoxy group of 1-16 carbon atoms, a hydrogen atom, or a halogenatom; and X is a group represented by —(C_(a)H_(b)F_(c))—, a is aninteger of 1-12, b+c=2a, b is an integer of 0-24, c is an integer of0-24. X is preferably a group having a fluoroalkylene group and analkylene group.

The matrix having the above constituting units is usually derived from afluorine-containing silicone compound having a fluoroalkyl grouprepresented by Formula (4) or (5).

where R¹ is a fluoroalkyl or perfluoroalkyl group of 1-16 carbons,preferably 3-12 carbons; R²-R⁷ are respectively an alkyl group of 1-16,preferably 1-4 carbon atoms, a halogenated alkyl group of 1-6,preferably 1-4 carbon atoms, an aryl group of 6-12, preferable 6-10carbon atoms, an alkylaryl or arylalkyl group of 7-14, preferably 7-12carbon atoms, an alkenyl group of 2-8, preferably 2-6 carbon atoms, oran alkoxy group of 1-6, preferably 1-3 carbon atoms, a hydrogen atom, ora halogen atom; and X is a group represented by —(C_(a)H_(b)F_(c))—,wherein a is an integer of 1-12, b+c=2a, b is an integer of 0-24, c isan integer of 0-24. X is preferably a group having a fluoroalkylenegroup and an alkylene group.

Specifically, the fluorine-containing silicone compound is exemplifiedby heptadecafluorodecylmethydimethoxysilane,heptadecafluorodecyltrichlorosilane,heptadecafluorodecyltrimethoxysilane, trifluorpropyltrimethoxysilane,tridecafluorooctyltrimethoxysilane, and a methoxysilane compoundrepresented by the formula (MeO)₃SiC₂H₄C₆F₁₂C₂H₄Si(MeO)₃.

The matrix containing a fluorine-substituted alkyl-containing siliconecomponent makes the resulting transparent coating film hydrophobic,which retards penetration of moisture or a chemical such as an acid oran alkali thereto, even when the transparent coating film is notsufficiently compact, or is porous, or has cracks or voids. Further withthis transparent coating film, the surface of the substrate or fineparticles of metal or the like in the underlying electroconductive layerdoes not cause reaction with the moisture or a chemical such as an acid,or a base. Thus such a transparent coating film has excellent chemicalresistance.

The matrix formed from a fluorine-substituted alkyl-containing siliconecomponent gives, to the resulting transparent coating film, not only thehydrophobicity but also a slipping property (low friction resistance) togive excellent scratch resistance.

Further, in the case where an electroconductive layer is employed, thematrix containing a fluorine-substituted alkyl-containing siliconecomponent can have a contraction coefficient nearly equal to that of theunderlying electroconductive layer, so that the resulting transparentcoating film has excellent adhesiveness to the underlyingelectroconductive layer. Furthermore, in heat treatment of thetransparent coating film, the electroconductive layer does neither causeexfoliation, nor cause local failure of electric contact in thetransparent electroconductive layer. Thus, the obtainable substrateformed electroconductive layer and transparent layer thereon securessufficient electroconductivity in the entire film.

The transparent coating film containing the fluorine-substitutedalkyl-containing silicone component and the inorganic compound particleshas not only the high scratch resistance but has high strength such asrubber eraser strength, and nail strength, and has high pencil hardness.

In the present invention, the matrix may contain a component other thanthe aforementioned fluorine-substituted alkyl-containing siliconecomponent. The other component mentioned here includes inorganic oxidessuch as silica, zirconia, and titania; and composite oxides such assilica-zirconia, silica-titania, and titania-zirconia. Of these, silicais particularly preferred.

The matrix contains the fluorine-substituted alkyl-containing siliconecomponent having the constitution units represented by the aboveFormulas (1) to (3) at a content ranging preferably from 0.1% to 70% byweight, more preferably from 1% to 30% by weight in terms of SiO₂ in thematrix.

At a content of less than 0.1% by weight of the fluorine-substitutedalkyl-containing silicone represented by the above Formulas (1) to (3)in the matrix in terms of SiO₂, the formed transparent coating film maynot have a sufficient slipping property and may not have sufficientscratch resistance.

The other component such as an inorganic oxide precursor, has a largercontraction coefficient than the fluorine-substituted alkyl-containingsilicone component. Therefore, increase of the other component willincrease the shrinkage of the transparent coating film, which may causewarpage of the substrate in the heat treatment (curing) of thetransparent coating film. In case of underlying the electroconductivefilm, exfoliation of the electroconductive layer or local electriccontact failure may be caused or by the difference in shrinkage betweenfilms. As a result, total electroconductivity of film becomesinsufficient. The increased shrinkage compactifies the film excessively,which may prevent the pore formation to weaken the effect of decrease ofthe refractive index of the transparent coating film. Further, the lesscontent of the fluorine compound of a low electron density tends torender the decrease of the refractive index of the transparent filminsufficient. Further the less content of the fluorine-substitutedalkyl-containing silicone component may make the hydrophobicity of thetransparent film insufficient, resulting low chemical resistance.

At a content of higher than 70% by weight of the fluorine-substitutedalkyl-containing silicone represented by the above Formulas (1) to (3)in the matrix in terms of SiO₂, the formed transparent coating film maybecome excessively porous to cause drop of the film strength, drop ofstrengths such as the rubber eraser strength- and scratch strength, andinsufficient adhesiveness to the substrate or the electroconductivelayer.

The matrix in the present invention has preferably a refractive index ofnot higher than 1.6. In the case where the matrix contains additionallya component other than the fluorine-substituted alkyl-containingsilicone component, the refractive index of the mixture thereof ispreferably not higher than 1.6.

The weight ratio of the matrix to the inorganic particles in thetransparent coating film (matrix/inorganic compound particles, both interms of the oxide) ranges preferably from 0.1 to 10, more preferablyfrom 0.2 to 5 in the present invention.

Transparent Film-Forming Liquid

The aforementioned transparent coating film is formed with a transparentfilm-forming liquid containing, for example, a matrix precursor and theinorganic compound particles.

Matrix Precursor

The matrix precursor includes the fluorine-containing silicone compoundsrepresented by Formula (4) or (5) shown before, hydrolysis productsthereof, and polycondensation products of the hydrolysis product(hereinafter referred to as a fluorine-substituted alkyl-containingsilicone precursor).

The fluorine-substituted alkyl-containing silicone precursor has anumber-average molecular weight ranging preferably from 500 to 10000,more preferably 700 to 2500 in terms of polystyrene.

The matrix precursor may contain the aforementioned inorganic oxideprecursor and/or an inorganic composite oxide precursor as necessary.

The inorganic oxide precursor and/or the inorganic composite oxideprecursor contained as necessary includes preferably silica precursors:in particular, preferred are partial hydrolysis products andhydrolysis-polycondensation products of hydrolyzable organic siliconcompounds, and silicic acid derived from aqueous alkali metal silicatesolution by dealkalization, especially, the silica precursor which is ahydrolysis-polycondensation products of the alkoxysilane represented byGeneral Formula [A] below:R_(a)Si(OR′)_(4-a)  [A]where R is a vinyl group, an aryl group, an acryl group, an alkyl groupof 1-8 carbon atoms, a hydrogen atom, or a halogen atom; R′ is a vinylgroup, an aryl group, an acryl group, an alkyl group of 1-8 carbonatoms, a hydrogen atom, a group of —C₂H₄OC_(n)H_(2n+1) (n=1-4), or ahydrogen atom; and a is an integer of 1-3.

The alkoxysilane includes tetramethoxysilane, tetraethoxysilane,tetraisopropoxysilane, tetrabutoxysilane, tetraoctylsilane,methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane,methyltriisopropoxysilane, vinyltrimethoxysilane,phenyltrimethoxysilane, and dimethyldimethoxysilane.

The silica precursor is a number-average molecular weight rangingpreferably from 500 to 10000 in terms of polystyrene. The silicaprecursor having a molecular weight of lower than 500 in terms ofpolystyrene may remain unhydrolyzed in the coating liquid, which maycause nonuniform application of the transparent coating film formingliquid on the electroconductive layer, or less adhesion of thetransparent coating film to the electroconductive film even if it can beuniformly applied. The silica precursor having a molecular weight ofhigher than 10000 in terms of polystyrene tends to lower the strength ofthe formed coating film.

In the mixture of the fluorine-substituted alkyl-containing siliconeprecursor and the inorganic oxide precursor and/or the inorganiccomposite oxide precursor, the fluorine-substituted alkyl-containingsilicone precursor constitutes the portion from 0.1% to 70%, morepreferably from 1% to 30% by weight in terms of oxides thereof.

With the fluorine-substituted alkyl-containing silicone precursor in amixing amount of less than 0.1% by weight (in terms of oxides), theformed transparent coating film shows a large shrinkage of the wholefilm owing to increasing the transparent portion of the optionally addedother component (inorganic oxide, etc.). This shrinkage may causewarpage of the substrate in the heat treatment (curing) of thetransparent coating film. In case of underlying the electroconductivefilm, exfoliation of the electroconductive layer or local electriccontact failure may be caused by the difference in shrinkage betweenfilms. As a result, total electroconductivity of film becomesinsufficient. The increased shrinkage compacts the transparent filmexcessively, which may lower the porosity of the film to weaken theeffect of decrease of the refractive index of the transparent coatingfilm. Further the lower content of the fluorine-substitutedalkyl-containing silicone precursor may decrease the hydrophobicity ofthe transparent film, resulting in low chemical resistance.

With the fluorine-substituted alkyl-containing silicone precursor in amixing amount of more than 70% by weight, the formed transparent coatingfilm may become excessively porous to cause drop of the film strength,and insufficient adhesiveness to the substrate or the underlyingelectroconductive layer.

In the transparent coating film formed by use of a transparent coatingfilm-forming liquid containing a fluorine-substituted alkyl-containingsilicone precursor as the matrix precursor as in the present invention,a part of the hydrophobic fluorine-substituted alkyl group covers thefine metal particles on the electroconductive layer surface to form aprotection layer composed of hydrophobic fluorine-substituted alkylgroup-containing silicone component at the interface between theelectroconductive layer and the transparent layer, thereby improving thechemical resistance of the electroconductive layer.

The fluorine-substituted alkyl-containing silicone precursor tends tohave a two-dimensional chain structure. Such a fluorine-substitutedalkyl-containing silicone precursor of two-dimensional chain structurecan readily be adsorbed by or readily bond to the inorganic compoundparticles in comparison with the inorganic oxide precursor like thesilica matrix precursor. Therefore, in the transparent coatingfilm-forming liquid, the aggregation of the inorganic compound particlesis prevented by the fluorine-substituted alkyl-containing siliconeprecursor to disperse the inorganic compound particles uniformly in thetransparent coating film-forming liquid. This transparent coatingfilm-forming liquid forms a transparent coating film in which theinorganic compound particles are uniformly dispersed. Such a transparentcoating film-forming liquid enables formation of a transparent coatingfilm on a large substrate with uniform dispersion of the inorganiccompound particles with excellent film appearance. Further, the processof the transparent coating film formation by use of the aforementionedtransparent coating film-forming liquid is industrially reliable andgives a high product yield.

In application and drying treatment of the transparent film-formingliquid, the evaporation of the solvent increases the concentration ofthe inorganic compound particles and the fluorine-substitutedalkyl-containing silicone precursor in the upper layer portion of thetransparent coating film. In the transparent coating film, thefluorine-containing silicone compound shrinks less and retains theporosity, showing a low refractive index, and the inorganic compoundparticles has inherently a low refractive index, thereby the refractionindex of the surface portion of the transparent coating layer makeslower. Since the fluorine-substituted alkyl-containing siliconeprecursor is concentrated the surface portion of the transparent coatinglayer as mentioned above, the transparent film surface has excellentslipping property, and has a high scratch strength. In the lower portionof the transparent coating layer, the inorganic oxide precursor like thesilica matrix precursor other than the fluorine-substitutedalkyl-containing silicone precursor are concentrated. This inorganicoxide precursor has a refractive index higher than that of thefluorine-substituted alkyl-containing silicone precursor and of theinorganic compound particles. Therefore, the transparent coating filmhas a refractive index gradient such that the refractive index decreasesfrom the layer bottom portion toward the layer surface portion of thetransparent coating film, which lowers the reflectivity, especially theluminous reflection factor, of the transparent coating film.

Thus, the transparent coating film formed from the coating liquidcontaining the aforementioned matrix precursor has a low refractiveindex, which gives a transparent film-coated substrate having excellentanti-reflection property.

Preparation of Transparent Coating Film-forming Liquid

The transparent coating film-forming liquid is prepared by mixing aliquid dispersion containing the matrix precursor, and theaforementioned inorganic compound particles.

The matrix precursor dispersion is prepared by dissolving or dispersingthe fluorine-substituted alkyl-containing silicone precursor, andoptionally an precursor of an oxide like silica in a water-alcohol mixedsolvent. The matrix precursor dispersion may also be prepared bydissolving or dispersing a substitute alkyl-containing precursor andoptionally a precursor to an oxide like silica in a water-alcohol mixedsolvent, and hydrolyzing them in the presence of an acid catalyst.

The inorganic compound particles is contained in the transparentfilm-forming liquid in an amount ranging preferably from 0.05% to 3%,more preferably from 0.2% to 2% by weight in terms of the oxide. At theconcentration of the inorganic compound particles of lower than 0.05% byweight in the transparent film-forming liquid, the formed transparentcoating film has insufficient anti-reflection property owing toinsufficient amount of the inorganic compound particles, whereas at theconcentration higher than 3% by weight, cracks may be formed or the filmstrength may be lowered.

The matrix precursor is contained in the coating liquid at aconcentration ranging preferably from 0.05% to 10%, more preferably from0.1% to 5.0% by weight.

At the concentration of the matrix precursor of lower than 0.05% byweight in terms of the oxide in the coating liquid, the formed film isinsufficient in water resistance and anti-reflection property owing toinsufficient thickness of the formed film. At such a concentration ofthe matrix precursor, a sufficient thickness of the layer may not beobtained by one application, and may give nonuniform thickness of thefilm by repeated application. On the other hand, at the concentration ofthe matrix precursor of higher than 10% by weight in terms of the oxide,cracks may be caused or the film strength may be lower, or theanti-reflection property may be insufficient owing to the largerthickness of the film.

The weight ratio of the matrix precursor to the inorganic compoundparticles (matrix precursor/inorganic compound particles, both in termsof the oxide) ranges preferably from 0.1 to 10, more preferably from 0.2to 5.

The transparent film-forming liquid may contain further a fineparticulate composed of a low-refractivity material such as magnesiumfluoride, or may contain an additive such as an electroconductiveparticulate and/or a dye or a pigment in a small amount not to hinderthe transparency or the anti-reflection property of the transparentfilm.

Formation of Transparent Film

The method of formation of the transparent film is not speciallylimited. The film can be formed by a wet thin-film forming process inwhich the aforementioned coating liquid is applied by dip coating,spinner coating, spray coating, roll coater coating, flexographicprinting or the like method, and the applied liquid is dried.

The thickness of the formed transparent coating film ranges preferablyfrom 50 to 300 nm, more preferably from 80 to 200 nm to obtain highwater resistance, and excellent anti-reflection property with low bottomreflectivity and low luminous reflection factor. The transparent coatingfilm of the thickness of less than 50 nm may be inferior in filmstrength, water resistance, anti-reflection property, and so forth,whereas the transparent film of the thickness of more than 300 nm maycause cracking therein, or have lower film strength, or insufficientanti-reflection property owing to the excessive film thickness.

The coating film formed by application of the transparent coatingfilm-forming liquid during or after drying, in the present invention,may be heat-treated at a temperature of 100° C. or higher; or subjectedto irradiation of an electromagnetic wave having a wavelength shorterthan visible light such as ultraviolet ray, electron ray, X-ray, andγ-ray; or exposed to an atmosphere of an active gas such as ammonia.This treatment can promote the cure of the film-forming components andcan increase the hardness of the formed transparent film.

An anti-glaring transparent film-coated substrate causing less glaringcan be obtained, in formation of the coating film by application of thetransparent film-forming liquid, by applying the transparentfilm-forming liquid by spraying with the substrate kept at a temperaturefrom about 40 to about 90° C. to form ring-shaped rises.

The transparent film may be constituted of two or more coating layershaving different refractive indexes. For example, formation oftransparent coating films having refractive indexes decreasingsuccessively from the substrate surface can give transparent film-coatedsubstrate having excellent anti-reflection property. In this case, thelower transparent coating film need not contain the aforementionedinorganic compound particles and the fluorine-substitutedalkyl-containing silicone component.

In the case where the transparent film is formed on a electroconductivefilm surface, the difference of the refractive index between theelectroconductive film and the transparent film is preferably not lessthan 0.3. With the refractive index difference of less than 0.3, theanti-reflection property may be insufficient.

Display Device

The display device of the present invention has a front face plateconstituted of the aforementioned transparent film-coated substrate, andthe transparent film is placed on the outside face of the front faceplate.

Of the transparent film-coated substrates of the present invention, theone having an electroconductive layer of a surface resistance of nothigher than 10¹² Ω/□ has excellent anti-reflection property on thesurface of the electroconductive layer in the visible light region andthe near infrared region, and is suitable as a front face plate of adisplay device (e.g., a glass panel of a cathode-ray tube).

The display device of the present invention is a device for displayingan image electrically such as Brown tubes (CRT), fluorescent displaydevices (FIP), plasma display devices (PDP), and liquid crystal displaydevice (LCD), having a front face plate constituted of the transparentfilm-coated substrate. The front face plate may be a display face panelhaving an electroconductive film and a transparent film formed thereon,or a front face plate having an electroconductive film and a transparentfilm on a substrate provided separately from the display face panel.

A display device having a conventional front face plate, during running,would collect dirt on the front face plate, or emit an electromagneticwave through the front face plate. However, the one provided with afront face plate having an electroconductive layer of the surfaceresistance of 10¹² Ω/□ does not tend to collect dirt, and in particularthe one provided with a front face plate having an electroconductivelayer of the surface resistance of 10²-10⁴ Ω/□ will shield effectivelythe electromagnetic wave emission and an electromagnetic field generatedby the electromagnetic wave.

Light reflection on the front face plate of the display device hindersobservation of the displayed image. However, the display device of thepresent invention has a front face plate constituted of a substratecoated with a transparent film of low refractivity to lower the bottomreflectivity and luminous reflection factor, whereby the lightreflection can be effectively prevented in the wavelength range ofvisible light and near infrared light.

This display device, which has the transparent coating film of highscratch resistance on the surface of the front face plate, is notscratched on the face to maintain clear image formation for a long term.

The front face plate of a Brown tube, which is constituted of atransparent film-coated substrate containing a small amount of a dye orpigment in the transparent electroconductive layer or the transparentcoating film, absorbs an inherent wavelength of light with the dye orpigment to improve the contrast of the image displayed by the Browntube.

The front face plate of the Brown tube is coated with the transparentcoating film containing inorganic compound particles of low refractiveindex of the present invention to give excellent anti-reflectionproperty, thereby enabling clear image display without scattering ofvisible light. This transparent film adheres well to theelectroconductive layer to serve also as a protection film to maintainthe high display performance for a long term. Further, this stableelectroconductivity of the electroconductive film keeps the anti-staticproperty and the electromagnetic shielding property for a long term.

The transparent film-coated substrate of the present invention has atransparent coating film which contains inorganic compound particles ofa low refraction index and a fluorine-substituted alkyl-containingsilicone component. In this transparent film-coated substrate, thetransparent film has high adhesiveness to the substrate or theelectroconductive layer, and has high scratch resistance, high waterresistance, and high chemical resistance. Further, the transparentcoating film has a low bottom reflectivity and a low luminous reflectionfactor to lead to excellent anti-reflection property over a broadwavelength region of the visible light.

The transparent coating film-forming liquid of the present invention isuseful for formation of the aforementioned transparent film-coatedsubstrate.

The display device of the present invention has a front face plate whichhas an excellent anti-reflection property and a high water resistance,thereby giving a sharp display image without scattering of visible lightand maintaining the display performance for a long term. With anelectroconductive film formed, the high chemical resistance of thetransparent coating film maintains the electroconductivity for a longterm without deterioration of the anti-static property and theelectromagnetic wave-shielding performance.

EXAMPLES

The present invention is described in more detail by reference toexamples without limiting the invention thereto.

Preparation Example 1

Preparation of Inorganic Compound Particle P-1 (Porous Matter Enclosedby Shell)

A 100 g portion of silica sol having average particle diameter of 5 nmand containing SiO₂ at a concentration of 20% by weight, and 1,900 g ofpure water were mixed to prepare a reaction mother liquor. The motherliquor was heated to 80° C. The mother liquor had a pH of 10.5. To themother liquor were added simultaneously 9,000 g of aqueous sodiumsilicate solution (1.5% by weight in terms of SiO₂) and 9,000 g ofsodium aluminate (0.5% by weight in terms of Al₂O₃) by keeping thetemperature at 80° C. The pH of the reaction solution rose to 12.5immediately after the addition of the sodium silicate and the sodiumaluminate, and was nearly constant thereafter. After completion of theaddition of the solutions, the reaction liquid was cooled to roomtemperature and washed by ultrafiltration to obtain a liquid dispersion(A) of a porous material precursor particle containing SiO₂.Al₂O₃ at asolid matter concentration of 20% by weight. (Step 1)

To 500 g of this dispersion (A) of porous material precursor particle,1,700 g of pure water was added, and the mixture was heated to 98° C.Thereto, by keeping this temperature, 3,000 g of silicic acid solution(SiO₂: 3.5% by weight) obtained by dealkalizing an aqueous sodiumsilicate solution contacted with cation exchange was added to form aprotecting silica film on the surface of the porous material precursorparticle. The obtained dispersion of porous material precursor particlewas washed by ultrafiltration to adjust the solid matter concentrationto 13% by weight. To 500 g of this liquid dispersion of porous materialprecursor particle, 1,125 g of pure water was added, and furtherconcentrated hydrochloric acid (35.5% by weight) was added to adjust thepH to 1.0 to remove aluminum.

Then with addition of 10 L (Litter) of aqueous hydrochloric acidsolution (pH 3) and 5 L (Litter) of pure water, the dissolved aluminumsalt was separated by ultrafiltration to obtain a liquid dispersion (B)of a porous SiO₂.Al₂O₃ particles with the aluminum partly removed. (Step2)

A 1,500 g portion of the above liquid dispersion (B) of the porousparticle, 500 g of pure water, 1,750 g of ethanol, and 626 g of aqueous28% ammonia were mixed, and the mixture was heated to 35° C. Thereto 104g of ethyl silicate (SiO₂: 28% by weight) was added to form a silicashell layer composed of ethyl silicate hydrolysis-polycondensationproduct on the surface of the porous particles. Then the liquid wasconcentrated to a solid matter concentration of 5% by weight by anevaporator. Thereto aqueous 15% by weight ammonia solution was added toadjust pH to 10. The liquid was heat-treated at 180° C. for 2 hours inan autoclave. The solvent was replaced with ethanol by use of anultrafiltration membrane to obtain a liquid dispersion of inorganiccompound particle (P-1) at a solid matter concentration of 20% byweight. (Step 3)

Table 1 shows the properties of this particle (P-1): the averageparticle diameter, the molar ratio SiO₂/MO_(x) of the whole particle(including the formed shell layer) and the refractive index. The averageparticle diameter was measured by dynamic light scattering, and therefractive index was measured by the procedure shown below in thepresent invention.

Measurement of Refraction Index of Particle

-   (1) Coating liquids for refractive index measurement were prepared    by mixing an SiO₂ matrix forming liquid (M) prepared in Preparation    Example 9 shown later and the inorganic compound particle at weight    ratios of the matrix (weight in term of SiO₂) to inorganic compound    particles (weight in term of oxides) of 100:0, 90:10, 80:20, 60:40,    50:50, and 25:75 respectively in terms of the oxide.-   (2) The coating liquids were applied respectively on a silicon wafer    having the surface kept at 50° C. by a spinner method at 300 rpm.    The coated films were heat-treated at 160° C. for 30 minutes. The    refractive indexes of the respective formed coating films for    refractive index measurement were measured respectively by an    ellipsometer.-   (3) The obtained refractive indexes were plotted as a function of    the particle mixing ratio:-   (Particle: (MO_(x)+SiO₂)/[Particle:(MO_(x)+SiO₂)+Matrix:SiO₂]). The    plots were extrapolated to 100% particle content.-   (4) The void volume ratio was estimated by calculating the air    volume from the difference between the above obtained refractive    index and the refractive index (1.45) of pure SiO₂ to obtain the    void volume ratio.

Preparation Example 2

Preparation of Inorganic Compound Particle P-2 (Porous Matter Enclosedby Shell)

To 100 g of the liquid dispersion (A) of the porous material precursorparticle obtained above, 1,900 g of pure water was added and the mixturewas heated to 95° C. By keeping this temperature, 27,000 g of an aqueoussodium silicate solution (1.5% by weight in terms of SiO₂), and 27,000 gof an aqueous sodium aluminate solution (0.5% by weight in terms ofAl₂O₃) were added gradually concurrently to grow particles by utilizing,as seed, the particles of the liquid dispersion (A) of the porousmaterial precursor particle. After completion of the addition, themixture was cooled to room temperature, and washed and concentrated byultrafiltration to obtain a liquid dispersion (C) of a porous materialprecursor particle containing SiO₂.Al₂O₃ at a solid matter concentrationof 20% by weight. (Step 1)

A 500 g portion of this liquid dispersion (C) of the porous materialprecursor particle was treated in the same manner as in PreparationExample 1 to form a protecting silica film of Step 2. The liquid mixturewas treated for aluminum removal. Then the silica shell layer was formedwith ethylsilicate hydrolysis product as Step 3 to prepare the liquiddispersion of the inorganic compound particle (P-2). Table 1 shows theproperties of the particle.

Preparation Example 3

Preparation of Inorganic Compound Particle P-3 (Porous Matter Enclosedby Shell)

To 100 g of the liquid dispersion (C) of the porous material precursorparticle obtained above, 1,900 g of pure water was added and the mixturewas heated to 95. By keeping this temperature, 7,000 g of an aqueoussodium silicate solution (1.5% by weight in terms of SiO₂), and 7,000 gof an aqueous sodium aluminate solution (0.5% by weight in terms ofAl₂O₃) were added gradually concurrently to grow particles. Aftercompletion of the addition, the mixture was cooled to room temperature,and washed and concentrated by ultrafiltration to obtain a liquiddispersion (D) of a porous material precursor particle containingSiO₂.Al₂O₃ at a solid matter concentration of 13% by weight.

To 500 g of this liquid dispersion (D) of the porous material precursorparticle, 1,125 g of pure water was added, and thereto hydrochloric acid(35.5%) was added dropwise to adjust the pH to 1.0. The liquid mixturewas treated for aluminum removal.

The dissolved aluminum salt was removed with addition of 10 L of anaqueous hydrochloric acid solution and 5 L of pure water byultrafiltration to obtain a liquid dispersion (E) of a porous materialprecursor particle composed of SiO₂.Al₂O₃ with the aluminum partlyremoved.

A 1,500 g portion of the above liquid dispersion (E) of the porousparticle, 500 g of pure water, 1,750 g of ethanol, and 626 g of aqueous28% ammonia were mixed, and the mixture was heated to 35. Thereto 210 gof ethyl silicate (SiO₂ content: 28% by weight) was added to form asilica shell layer composed of ethyl silicatehydrolysis-polycondensation product on the surface of the porousparticles. Then the liquid was condensed to a solid matter concentrationof 5% by weight by an evaporator. Thereto aqueous 15% by weight ammoniasolution was added to adjust pH to 10. The liquid was heat-treated at180. for 2 hours in an autoclave. The solvent was replaced with ethanolby ultrafiltration to obtain a liquid dispersion of inorganic compoundparticle (P-3) (solid matter concentration: 20% by weight). Table 1shows the properties of the particle.

Preparation Example 4

Preparation of Inorganic Compound Particle P-4 (Cavity Enclosed byShell)

A 10 g portion of silica sol having average particle diameter of 5 nmand containing SiO₂ at a concentration of 20% by weight, and 190 g ofpure water were mixed to prepare a reaction mother liquor. The motherliquor was heated to 95. This mother liquor had a pH of 10.5. To themother liquor, were added simultaneously 24,900 g of aqueous sodiumsilicate solution (1.5% by weight in terms of SiO₂) and 36,800 g ofaqueous sodium aluminate solution (0.5% by weight in terms of Al₂O₃)while keeping the temperature at 95. The pH of the reaction solutionrose to 12.5 immediately after the addition of the sodium silicate andthe sodium aluminate, and was nearly constant thereafter. Aftercompletion of the addition of the solutions, the reaction liquid wascooled to room temperature, and washed by ultrafiltration to obtain aliquid dispersion (F) of a porous material precursor particle containingSiO₂.Al₂O₃ at a solid matter concentration of 20% by weight.

(Step 1)

To 500 g of this liquid dispersion (F) of porous material precursorparticle, 1,700 g of pure water was added, and the mixture was heated to98° C. Thereto, by keeping this temperature, 3,000 g of silicic acidsolution (SiO₂ concentration: 3.5% by weight) obtained by dealkalizingan aqueous sodium silicate solution contacted with cation exchange resinwas added to form a protecting silica film on the surface of the porousmaterial precursor particle. The obtained liquid dispersion of porousmaterial precursor particle was washed by ultrafiltration to adjust thesolid matter concentration to 13% by weight. To 500 g of this liquiddispersion of porous material precursor particle, 1,125 g of pure waterwas added, and further concentrated hydrochloric acid (35.5% by weight)was added to adjust the pH to 1.0 to remove aluminum. Then with additionof 10 L of aqueous hydrochloric acid solution (pH 3) and 5 L of purewater, the dissolved aluminum salt was separated by ultrafiltration toobtain a liquid dispersion of a particle precursor.

(Step 2)

A 1,500 g portion of the above liquid dispersion of the particleprecursor, 500 g of pure water, 1,750 g of ethanol, and 626 g of aqueous28% ammonia were mixed, and the mixture was heated to 35° C. Thereto 104g of ethyl silicate (SiO₂ content: 28% by weight) was added to form asilica shell layer composed of ethyl silicatehydrolysis-polycondensation product on the surface of the particleprecursor. Then the liquid was condensed to a solid matter concentrationof 5% by weight by an evaporator. Thereto aqueous 15% by weight ammoniasolution was added to adjust pH to 10. The liquid was heat-treated at180° C. for 2 hours in an autoclave. The solvent was replaced withethanol by ultrafiltration to obtain a liquid dispersion of inorganiccompound particle (P-4) at a solid matter concentration of 20% byweight.

(Step 3)

The cross section of the particle was observed by transmission typeelectron microscope (TEM). The particles had a cavity enclosed by theshell layer as shown in FIG. 2.

Preparation Example 5

Preparation of Inorganic Compound Particle P-5 (Porous Matter Enclosedby Shell)

A porous material precursor particle composed of SiO₂.SnO₂ having asolid matter concentration of 20% by weight was obtained in the samemanner as in preparation of the inorganic compound particle (P-1) exceptthat 9,000 g of aqueous 5% by weight potassium stannate solution wasused as the SnO₂ source in place of sodium aluminate in preparation ofthe inorganic compound particle (P-1). This precursor particle wastreated for formation of a protecting silica film in the same manner astreatment of inorganic compound particle (P-1), and treated for Snremoval (the same treatment as the aluminum removal in PreparationExample 1), and for formation of silica shell layer to obtain a liquiddispersion of an inorganic compound particle (P-5). Table 1 shows theproperty of the inorganic compound particle.

Preparation Example 6

Preparation of Inorganic Compound Particle P-6 (Comparative Example:Shell Not Formed)

An inorganic compound particle (P-6) was prepared in the same manner aspreparation of the inorganic compound particle (P-1). A 100 g portion ofa silica sol having average particle diameter of 5 nm and containingSiO₂ at a concentration of 20% by weight, and 1,900 g of pure water weremixed. The mixture was heated to 80° C. This reaction liquid had a pH of10.5. To the reaction liquid were added simultaneously 9,000 g ofaqueous sodium silicate solution (1.5% by weight in terms of SiO₂) and9,000 g of sodium aluminate solution (0.5% by weight in terms of Al₂O₃)with keeping the temperature at 80° C. The pH of the reaction solutionrose to 12.5 immediately after the addition of the sodium silicate andthe sodium aluminate, and was nearly constant thereafter. Aftercompletion of the addition of the solutions, the reaction liquid wascooled to room temperature, and washed by ultrafiltration to obtain aliquid dispersion of a porous material particle (P-6) containingSiO₂.Al₂O₃ at a solid matter concentration of 20% by weight.

Preparation Example 7

Preparation of Inorganic Compound Particle P-7 (Comparative Example:Shell Not Formed)

A 100 g portion of methylsilicate (SiO₂ content: 39% by weight) and 530g of methanol were mixed, and thereto 79 g of an aqueous 28% by weightammonia solution was added. The mixture was stirred at 35° C. for 24hours. The particle was washed, and the solvent was replaced withethanol by ultrafiltration. As a result, a liquid dispersion of a poroussilica particle (P-7) was obtained which has a solid matterconcentration of 20% by weight. Table 1 shows the properties of theporous particle.

TABLE 1 Inorganic Compound Particle Porous matter Porous precursorparticle matter particle Silica shell layer Inorganic compound particleMolar Molar Average Thickness of Molar Average ratio ratio particleprotecting ratio particle Oxide MO_(x)/ MO_(x)/ diameter silica layerThickness¹⁾ MO_(x)/ diameter Void ratio No. composition SiO₂ SiO₂ (nm)(nm) (nm) SiO₂ (nm) Refractivity (Volume %) P-1 Alumina/silica 0.1710.0118 24 1 3 0.00786 30 1.40 11.1 P-2 Alumina/silica 0.195 0.0105 48 26 0.00695 60 1.37 17.7 P-3 Alumina/silica 0.196 0.0076 73 — 10 0.0047893 1.35 22.2 P-4 Alumina/silica 0.288 0.0035 76 3 10 0.00217 96 1.3131.1 P-5 Tin oxide/silica 0.116 0.0121 22 1 4 0.00806 30 1.40 11.1 P-6Porous silica · alumina²⁾ Not formed 0.171 20 1.56 2.5 P-7 Poroussilica²⁾ Not formed 0 25 1.43 4.4 ¹⁾Particles P-1, P-2, P-4 and P-5 havea protecting silica film formed: the thickness of the silica shell layerincluding the thickness of the protecting silica film ²⁾Particles P-6and P-7 employ originally porous particle without a shell layer³⁾Particle P-4 has a cavity inside

Preparation Example 8

Preparation of Electroconductive Particle Liquid Dispersion

(1) Liquid Dispersions (S-1, S-2) of a Metal Composite Particle (Q-1,Q-2) were Prepared in a Manner Shown Below.

To 100 g of pure water, trisodium citrate was preliminarily added in anamount corresponding to 0.01 part by weight based on one part by weightof fine composite metal particle to be formed. Thereto, an aqueoussilver nitrate solution and an aqueous palladium nitrate solution wereadded in a total amount of 10% by weight in terms of the metals at theweight ratio of the metals constituting the composite metal particle asshown in Table 2. Further thereto, an aqueous ferrous sulfate solutionwas added in an amount equivalent to the total moles of the silvernitrate and the palladium nitrate in the liquid. The liquid mixture wasstirred in a nitrogen atmosphere for one hour to obtain a liquiddispersion of the composite metal particle having the composition shownin Table 2. The resulting dispersion was washed with water bycentrifugation to remove impurities. The separated solid matter wasdispersed. Thereto the solvent (1-ethoxy-2-propanol) shown in Table 4was added. The liquid dispersion was evaporated by a rotary evaporatorto remove water and to concentrate it. Thereby metal particle liquiddispersions (S-1, S-2) were obtained which had solid contents as shownin Table 2.

(2) A Liquid Dispersion (S-3) of a Tin-doped Indium Oxide Particle (Q-3)was Prepared in a Manner Shown Below.

A 79.9 g portion of indium nitrate was dissolved in 686 g of water.Separately, 12.7 g of potassium stannate was dissolved in a 10% byweight potassium hydroxide. These two solutions were added to 1000 g ofwater kept at 50° C. in two hours by keeping the pH at 11 during theaddition. From the resulting liquid dispersion, the formed hydrate oftin-doped indium oxide was collected by filtration, washed, dried, bakedat 350° C. for 3 hours in the air, and further baked at 600° C. for 2hours in the air to obtain tin-doped indium oxide particle (Q-3). Thisparticle was dispersed in pure water at a concentration of 30% byweight. The pH of the dispersion was adjusted to 3.5 by addition ofaqueous nitric acid. The liquid mixture was treated for pulverization bymeans of a sand mill at 30° C. for 3 hours to prepare a sol. This solwas treated for ion exchange to remove nitrate ions. Pure water wasadded thereto to prepare the liquid dispersion (S-3) of particletin-doped indium oxide (ITO) (Q-3) at the concentration shown in Table2.

(3) A Liquid Dispersion (S-4) of an Antimony-doped Tin Oxide Particle(Q-4) was Prepared in a Manner Shown Below.

In 100 g of methanol, were dissolved 57.7 g of tin chloride and 7.0 g ofantimony chloride. The solution was added gradually into 1000 g of purewater at 90° C. in 4 hours with stirring for hydrolysis. The resultingprecipitate was collected by filtration, washed, and dried, and thenfired in the air at 500° C. for 2 hours to obtain particleantimony-doped tin oxide. A 30 g portion of this powder was added to 70g of an aqueous potassium hydroxide solution. (corresponding to 3.0 g ofKOH). The mixture was grinded by means of a sand mill at 30° C. for 3hours to prepare a sol. This sol was contacted with ion exchange forresin dealkalization. Pure water was added thereto to prepare the liquiddispersion (S-4) of antimony-doped tin oxide (ATO) (Q-4) at theconcentration shown in Table 2.

Preparation Example 9

c) Preparation of Matrix-Forming Component Liquids

Preparation of Matrix-Forming Component Liquid (M-1)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),9.52 g of heptadecafluorodecyltrimethoxysilane, 194.6 g of ethanol, 1.4g of concentrated nitric acid, and 34 g of pure water was stirred atroom temperature for 5 hours to prepare a liquid (M-1) containing amatrix-forming component at a concentration of 5% by weight in terms ofSiO₂.

Preparation of Matrix-Forming Component Liquid (M-2)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),47.5 g of heptadecafluorodecyltrimethoxysilane, 194.6 g of ethanol, 1.4g of concentrated nitric acid, and 34 g of pure water was stirred atroom temperature for 5 hours to prepare a liquid (M-2) containing amatrix-forming component at a concentration of 5% by weight in terms ofSiO₂.

Preparation of Matrix-Forming Component Liquid (M-3)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),6.57 g of (CH₃O)₃SiC₂H₄C₆F₁₂C₂H₄Si(CH₃O)₃, 194.6 g of ethanol, 1.4 g ofconcentrated nitric acid, and 34 g of pure water was stirred at roomtemperature for 5 hours to prepare a liquid (M-3) containing amatrix-forming component at a concentration of 5% by weight in terms ofSiO₂.

Preparation of Matrix-Forming Component Liquid (M-4)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),12.14 g of heptadecafluorodecyltrimethoxysilane, 194.6 g of ethanol, 1.4g of concentrated nitric acid, and 34 g of pure water was stirred atroom temperature for 5 hours to prepare a liquid (M-4) containing amatrix-forming component at a concentration of 5% by weight in terms ofSiO₂.

Preparation of Matrix-Forming Component Liquid (M-5)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),20.65 g of heptadecafluorodecyltrimethoxysilane, 194.6 g of ethanol, 1.4g of concentrated nitric acid, and 34 g of pure water was stirred atroom temperature for 5 hours to prepare a liquid (M-5) containing amatrix-forming component at a concentration of 5% by weight in terms ofSiO₂.

Preparation of Matrix-Forming Component Liquid (M-6)

A mixture of 50 g of ethyl orthosilicate (TEOS) (SiO₂: 28% by weight),194.6 g of ethanol, 1.4 g of concentrated nitric acid, and 34 g of purewater was stirred at room temperature for 5 hours to prepare a liquid(M-6) containing a matrix-forming component at a concentration of 5% byweight in terms of SiO₂.

Preparation Example 10

d) Preparation of Electroconductive Film-Forming Liquid

Electroconductive film-forming liquids (CS-1)-(CS-3) were prepared bymixing the liquid dispersion (S-1)-(S-3), the matrix-forming componentmixture (M-6), ethanol, and 1-ethoxy-2-propanol in a composition ratioshown in Table 4.

TABLE 2 Electroconductive Fine Particle Electroconductive Particle Solidmatter Particle Average concentration in liquid Particleelectroconductive dispersion Weight diameter particle liuqid No. No.Component ratio (nm) dispersion (wt %) S-1 Q-1 Ag/Pd 8/2 8 10 S-2 Q-2Ag/Pd 6/4 8 10 S-3 Q-3 ITO — 80 20 S-4 Q-4 ATO — 10 20 ITO: Tin-dopedindium oxide ATO: antimony-doped tin oxide

TABLE 3 Matrix-Forming Component Liquid Dispersion Solid Composition ofmatrix- matter forming component concen- Amount tration DispersionComponent (g) (wt %) M-1 Ethyl orthosilicate 50 5Heptadecafluorodecyltrimethoxysilane 9.52 M-2 Ethyl orthosilicate 50 5Heptadecafluorodecyltrimethoxysilane 47.5 M-3 Ethyl orthosilicate 50 5(CH₃O)₃SiC₂H₄C₆F₁₂C₂H₄Si(CH₃O)₃ 6.57 M-4 Ethyl orthosilicate 50 5Heptadecafluorodecyltrimethoxysilane 12.14 M-5 Ethyl orthosilicate 50 5Heptadecafluorodecyltrimethoxysilane 20.65 M-6 Ethyl orthosilicate 50 5

TABLE 4 Electroconductive Film-Forming Liquid Solid matter Weightconcentration Liquid Formulation parts (wt %) CS-1 Solid matter liquiddispersion S-1 10 0.24 M-6 4 Dispersion medium Ethanol 368.41-ethoxy-2-propanol 117.6 CS-2 Solid matter liquid dispersion S-2 100.24 M-6 4 Dispersion medium Isopropyl alcohol 368.4 t-butanol 117.6CS-3 Solid matter liquid dispersion S-3 10 2.00 Dispersion mediumethanol 54 1-ethoxy-2-propanol 36 CS-4 Solid matter liquid dispersionS-4 10 2.00 Dispersion medium ethanol 54 1-ethoxy-2-propanol 36

Example 1

Preparation of Transparent Film-Forming Liquid (B-1)

To the above liquid (M-1) containing the matrix-forming component, wasadded a mixed solvent of ethanol/butanol/diacetone alcohol/isopropylalcohol (mixing weight ratio of 2:1:1:5). Thereto, the above liquiddispersion of the inorganic compound particle (P-1) was added to preparea transparent film-forming liquid (B-1). Table 5 shows the concentrationof the inorganic compound particle in terms of a solid matter, and theconcentration of the matrix-forming component in terms of SiO₂.

Production of Transparent Film-Coated Glass Plate

The transparent film-forming liquid (B-1) was applied to form atransparent film in a thickness of 100 nm on a glass base plate having asurface kept at 40° C. by a spinner method under the conditions of 100rpm and 90 seconds. The film was dried and heated at 160° C. for 30minutes to obtain a transparent film-coated glass plate (G-1).

The above transparent film-coated glass plate was tested for haze andreflectivity. The haze was measured by a haze computer (Model: 3000A,manufactured by Nippon Denshoku K.K.). The reflectivity was measuredaccording to JIS Z8727 by a reflectometer (Model:MCPD-2000, manufacturedby Ohtsuka Denshi K.K.). The minimum reflectivity in the wavelengthrange from 400 nm to 700 nm is defined as the bottom reflectivity.

The average reflectivity in the wavelength range from 400 nm to 700 nmis defined as the luminous reflection factor which was measuredaccording to JIS Z8727. The diameter of the fine particle was measuredby a micro-track particle size tester (manufactured by Nikkiso Co.Ltd.).

The film strength was evaluated by rubber eraser strength and scratchstrength as shown below.

Rubber Eraser Strength

A piece of rubber eraser (1K, produced by Lion Corp.) was set on thetransparent film-coated glass plate with a load of 1±0.1 Kg applied onthe rubber eraser. The rubber eraser was moved forward and backward 25times at a stroke of about 25 mm. The formed scrapings were blown awayby compressed air at each reciprocating movement. After 25 times of thereciprocating movement, the surface of the transparent film was examinedvisually at a distance of 45 cm apart from the surface underillumination of 1000 lx.

Evaluation Standard:

A: No scratch is observed.

B: Color of reflection light of the fluorescent lamp light is changed(from violet to red).

C: No reflection of the fluorescent lamp light is observed, and scratchis observed.

D: The base plate is bared.

Scratch Strength

A standard test needle (Hardness: HRC-60, diameter 0.5 mm, produced byRockwell Co.) was set on the transparent film with a load of 1±0.3 Kg.The needle was moved to sweep the surface at a stroke of 30-40 mm. Thesurface of the coating film was examined visually 45 cm apart from thesurface under illumination of 1000 lx.

Evaluation Standard:

A: No scratch is observed.

B: Color of reflection of light of the fluorescent lamp light is changed(from violet to red).

C: No reflection of the fluorescent lamp light is observed, and scratchis observed.

D: The base plate is bared.

Table 6 shows the results.

Examples 2 to 6

Preparation of Transparent Film-Forming Liquid (B-2 to B-6)

The liquid (M-1 (M-4) containing a matrix-forming component, a mixedsolvent of ethanol/butanol/diacetone alcohol/isopropyl alcohol (mixingweight ratio of 2:1:1:5), and the above liquid dispersion of theinorganic compound particle (P-2, P-3, and P-5) or particle havingcavity (P-4) were mixed to prepare a transparent film-forming liquid(B-2)-(B-6). Table 5 shows the concentrations of the particle, and theconcentration of the matrix-forming component in terms of a solidmatter.

Production of Transparent Film-Coated Glass Plates

The transparent film-forming liquid (B-2)-(B-6) was applied to form atransparent film in a thickness of 100 nm on a glass base plate having asurface kept at 40° C. by a spinner method under the conditions of 100rpm and 90 seconds. The applied film was dried, and heated at 160° C.for 30 minutes to obtain a transparent film-coated glass plate(G-2)-(G-6).

The obtained transparent film-coated glass was evaluated in the samemanner as in Example 1. Table 6 shows the results.

Comparative Examples 1-5

Preparation of Transparent Film-Forming Liquid (B-7 to B-11)

The liquid (M-1), (M-5), or (M-6) containing the above matrix-formingcomponent, a mixed solvent of ethanol/butanol/diacetonealcohol/isopropyl alcohol (mixing weight ratio of 2:1:1:5), and theabove liquid dispersion of the inorganic compound particle (P-6, P-7,and P-1) were mixed to prepare a transparent film-forming liquid(B-7)-(B-11). Table 5 shows the concentrations of the particle, and theconcentration of the matrix-forming component in terms of a solidmatter.

Production of Transparent film-Coated Glass Plates

The transparent film-forming liquid (B-7)-(B-11) was applied to form atransparent film in a thickness of 100 nm on a glass base plate having asurface kept at 40° C. by a spinner method under the conditions of 100rpm and 90 seconds. The film was dried, and heated at 160° C. for 30minutes to obtain a transparent film-coated glass plate (G-7)-(G-11).

The obtained transparent film-coated glass was evaluated in the samemanner as in Example 1. Table 6 shows the results.

TABLE 5 Transparent Film-Forming Liquid Fluorine- substituted alkyl-Matrix-forming containing Matrix Inorganic component Particle siliconecomponent compound liquid concentration concentration concentrationLiquid particle dispersion (wt %) (wt %) (wt %) B-1 P-1 M-1 0.2 0.030.62 B-2 P-2 M-2 0.2 0.15 0.50 B-3 P-3 M-1 0.2 0.03 0.62 B-4 P-4 M-1 0.20.03 0.62 B-5 P-5 M-3 0.2 0.03 0.62 B-6 P-3 M-4  0.25 0.05 0.80 B-7 P-6M-1 0.2 0.03 0.62 B-8 — M-5 — 0.10 0.90 B-9 P-7 M-6 0.2 0.00 0.65 B-10P-7 M-1 0.2 0.05 0.60 B-11 P-1 M-6 0.2 0.00 0.65 Matrix componentconcentration includes the fluorine-substituted alkyl-containingsilicone concentration.

TABLE 6 Evaluation Results of Transparent Film-Coated Substrate,Electroconductive Layer Not Employed Transparent film-coated substrateTransparent Film strength Transparent film Bottom Luminous Rubberfilm-forming thickness reflectivity reflection Haze eraser Scratchliquid (nm) Refractivity (%) factor (%) (%) strength strength Example 1B-1 100 1.42 1.4 1.7 0.2 A A Example 2 B-2 100 1.40 1.3 1.4 0.1 A AExample 3 B-3 100 1.37 1.2 1.5 0.3 A A Example 4 B-4 100 1.34 1.1 1.40.2 A A Example 5 B-5 100 1.41 1.4 1.7 0.5 A A Example 6 B-6 100 1.371.2 1.5 0.2 A A Comp Ex. 1 B-7 100 1.46 2.0 2.4 1.2 A A Comp Ex. 2 B-8100 1.44 1.7 1.9 0.2 A C Comp Ex. 3 B-9 100 1.44 1.9 2.2 0.5 B C CompEx. 4 B-10 100 1.45 1.9 2.2 0.3 A B Comp Ex. 5 B-11 100 1.42 1.5 1.9 0.3A C

Example 7

Production of Transparent Film-Coated Glass Panel

The aforementioned electroconductive film-forming liquid (CS-1) wasapplied to form an electroconductive film in a thickness of 20 nm on aBrown tube glass panel (14″) having a surface kept at 40° C. by aspinner method under the conditions of 100 rpm and 90 seconds, and thefilm was dried.

Then the transparent film-forming liquid (B-1) was applied to form atransparent film in a thickness of 100 nm on the electroconductive layerby a spinner method under the conditions of 100 rpm and 90 seconds. Thefilm was dried, and baked at 160° C. for 30 minutes to obtain atransparent film-coated glass panel.

The above transparent film-coated glass panel was tested for haze andreflectivity. The haze was measured by a haze computer (Model: 3000A,manufactured by Nippon Denshoku K.K.). The reflectivity was measuredaccording to JIS Z8727 by a reflectometer (Model:MCPD-2000, manufacturedby Ohtsuka Denshi K.K.). The minimum reflectivity in the wavelengthrange from 400 nm to 700 nm is defined as the bottom reflectivity. Theaverage reflectivity in the wavelength range from 400 nm to 700 nm isdefined as the luminous reflection factor which was measured accordingto JIS Z8727.

The surface resistance of the transparent film-coated glass panel wasmeasured as follows. On the transparent film-coated glass panel, twosoldered electrodes were formed in parallel at a distance of 5 cm bymeans of an ultrasonic soldering machine (Model: SUNBONDER USM-III,solder line diameter 1.6 mm, melting temperature 224° C., manufacturedby Asahi Glass Co., Ltd.). Thereby, the solder electrodes wereelectrically connected through the transparent coating film with theelectroconductive layer. The outer electrodes were cut out. Theresistance between the electrodes was measured at a temperature of 23±5°C. and a relative humidity of 40% or lower in a desiccator by means ofan electric tester (Model: High Tester 3244, manufactured by HIOKI DenkiK.K.).

The adhesiveness was tested as follows. The surface of the transparentcoating film was cut with a knife in 11 lines in the vertical directionand the lateral direction respectively to form 100 cut squares on thesurface. Thereto a pressure-sensitive adhesive tape was put to adhereonce. Then the adhesive tape was peeled. The adhesiveness of the coatingfilm was evaluated on two levels from the number of the cut squaresremaining unpeeled according to the evaluation standard below.

-   -   Good: 95 or more cut squares remain unpeeled.    -   No good: 94 or less cut squares remain unpeeled.

A display device was assembled with the transparent film-coated panelplate for evaluation of the display performance. The display performanceis evaluated from the quality of the displayed image, the degree ofreflection of a fluorescent lamp light (mirror reflection of the lamp)placed at a distance of 5 m apart from the displaying face, and thecoloring degree according to the evaluation standard below.

-   -   AA: The reflection (mirror reflection) and the coloring are        weak, and the image is sharp.    -   A: The reflection (mirror reflection) is weak, and coloring is        observed, but the image is sharp.    -   B: The reflection (mirror reflection) and the coloring are        remarkable, and the image is partly unsharp.    -   C: The reflection (mirror reflection) and the coloring are        remarkable, and the image reflection is sharper than the        displayed image.

The film strength was evaluated by the rubber eraser strength and thescratch strength as below.

Rubber Eraser Strength

A piece of rubber eraser (1K, produced by Lion Corp.) was set on thetransparent film-coated glass plate with a load of 1±0.1 Kg applied onthe rubber eraser. The rubber eraser was moved forward and backward 25times at a stroke of about 25 mm. The formed scrapings were blown awayby compressed air at each reciprocating movement. After 25 times of thereciprocating movement, the surface of the transparent film was examinedvisually at a distance of 45 cm apart from the surface underillumination of 1000 lx.

Evaluation Standard:

-   -   A: No scratch is observed.    -   B: Color of reflection of the fluorescent lamp light is changed        (from violet to red).    -   C: No reflection of the fluorescent lamp light is observed, and        scratch is observed.    -   D: The base plate is bared.        Scratch Strength

A standard test needle (Hardness: HRC-60, diameter 0.5 mm, produced byRockwell Co.) was set on the transparent film with a load of 1±0.3 Kg.The needle was moved to sweep the surface at a stroke of 30-10 mm. Thesurface of the coating film was examined visually 45 cm apart from thesurface under illumination of 1000 lx.

Evaluation Standard:

-   -   A: No scratch is observed.    -   B: Color of reflection of the fluorescent lamp light is changed        (from violet to red).    -   C: No reflection of the fluorescent lamp light is observed, and        scratch is observed.    -   D: The base plate is bared.

The water resistance and the chemical resistance were evaluated asbelow.

Water Resistance

The transparent film-coated base plate was immersed in boiling distilledwater of 100° C. for 30 minutes. Thereafter, the surface resistance, thereflectivity, and the haze were measured in the same manner as above.

Chemical Resistance (1)

The transparent film-coated base plate was immersed in an aqueous 5% byweight hydrochloric acid solution for 10 hours. Thereafter, the surfaceresistance, the reflectivity, and the haze were measured in the samemanner as above.

Chemical Resistance (2)

The transparent film-coated base plate was immersed in an aqueous 5% byweight hydrochloric acid solution for 200 hours. Thereafter, the surfaceresistance, the reflectivity, and the haze were measured in the samemanner as above.

Table 7 shows the results.

Examples 8-14

Transparent Film-Coated Glass Panel

An electroconductive layer was formed from the electroconductivefilm-forming liquid (CS-1)-(CS-4) in a thickness as shown in Table 7 inthe same manner as in Example 7. Thereon, a transparent film was formedfrom the aforementioned transparent-film forming liquid (B-2)-(B-6) inthe same manner as in Example 7 to produce a transparent film-coatedsubstrate.

The obtained transparent film-coated substrate was evaluated for thesurface resistance, haze, reflectivity, adhesiveness, film strength, anddisplay performance. Table 7 shows the evaluation results. The waterresistance, the chemical resistance (1), and the chemical resistance (2)were also evaluated in the same manner as in Example 7. In Example 12,the chemical resistance (2) was not evaluated. Table 7 shows theresults. Furthermore, FIG. 4 shows reflectivity curve in the wavelengthregion of 400 to 700 nm of the transparent film coated substrate ofExample 13. The luminous reflection factor measured is calculated basedon the datum such as FIG. 4.

Comparative Examples 6-12

Transparent Film-Coated Glass Panel

In Comparative Examples 6-9 and 12, an electroconductive layer (20 nmthick) was formed from the electroconductive film-forming liquid (CS-1)in the same manner as in Example 7. Thereon, a transparent film wasformed from the aforementioned transparent-film forming liquid(B-7)-(B-11) in the same manner as in Example 7 to produce a transparentfilm-coated substrate.

In Comparative Example 10, an electroconductive layer (100 nm thick) wasformed from the electroconductive film-forming liquid (CS-3) in the samemanner as in Example 12. Thereon, a transparent film was formed from thetransparent-film forming liquid (B-9) in the same manner as in Example 6to produce a transparent film-coated substrate.

In Comparative Example 11, an electroconductive layer (20 nm thick) wasformed from the electroconductive film-forming liquid (CS-4) in the samemanner as in Example 13. Thereon, a transparent film was formed from thetransparent-film forming liquid (B-9) in the same manner as in Example 6to produce a transparent film-coated substrate.

The obtained transparent film-coated substrate was evaluated for thesurface resistance, haze, reflectivity, adhesiveness, film strength, anddisplay performance. Table 7 shows the evaluation results. The waterresistance, the chemical resistance (1), and the chemical resistance (2)were also evaluated as in Example 7. In Comparative Example 10, thechemical resistance (2) was not evaluated. Table 7 shows the results.

TABLE 7 Properties of Transparent Film-Coated Substrate,Electroconductive Layer Employed Electroconductive layer Electro-Transparent film-coated substrate conductive Electro- Transparent filmLuminous film- Thick- conduc- Transparent Inorganic Surface Bottomreflection forming ness tive film-forming Thickness compound resistancereflectivity factor Haze liquid (nm) particle liquid (nm) particle Ω/□(%) (%) (%) Adhesiveness Example 7 CS-1 20 Ag/Pd B-1 100 shell(1) 1,8000.05 0.25 0.05 Good Example 8 CS-1 20 Ag/Pd B-2 100 shell(1) 1,800 0.030.20 0.05 Good Example 9 CS-1 20 Ag/Pd B-3 100 shell(1) 1,800 0.01 0.100.05 Good Example 10 CS-1 20 Ag/Pd B-4 100 shell(2) 1,800 0.01 0.08 0.05Good Example 11 CS-2 20 Ag/Pd B-5 100 shell(1) 1,800 0.06 0.28 0.05 GoodExample 12 CS-3 100 ITO B-6 100 shell(1) 5,000 0.50 0.65 0.70 GoodExample 13 CS-4 20 ATO B-6 100 shell(1) 6 × 10⁸ 0.45 0.55 0.50 GoodExample 14 CS-1 50 Ag/Pd B-1 100 shell(1) 800 0.01 0.25 0.10 Good CompEx. 6 CS-1 20 Ag/Pd B-7 100 porous matter 1,800 0.85 1.30 0.30 Good CompEx. 7 CS-1 20 Ag/Pd B-8 100 porous matter 2,000 0.55 0.95 0.80 Good CompEx. 8 CS-1 20 Ag/Pd B-9 100 porous matter 1,800 0.60 1.00 0.80 Good CompEx. 9 CS-1 20 Ag/Pd B-10 100 porous matter 1,800 0.55 0.95 0.80 GoodComp Ex. 10 CS-3 100 ITO B-9 100 porous matter 5,000 0.60 0.80 0.80 GoodComp Ex. 11 CS-4 20 ATO B-9 100 porous matter 6 × 10⁸ 0.55 0.70 0.70Good Comp Ex. 12 CS-1 20 Ag/Pd B-1 100 porous matter 1,800 0.10 0.350.10 Good Transparent film-coated substrate Water resistance Chemicalresistance (1) Chemical resistance (2) Film strength Luminous LuminousLuminous Rubber Surface reflection Surface reflection Surface reflectioneraser Scratch Display resistance factor Haze resistance factor Hazeresistance factor strength strength performance Ω/□ (%) (%) Ω/□ (%) (%)Ω/□ (%) Haze (%) Example 7 A B AA 1,800 0.25 0.30 1,900 0.26 0.10 2,1000.30 0.30 Example 8 A B AA 1,800 0.03 0.22 1,900 0.22 0.15 2,100 0.280.20 Example 9 A B AA 1,800 0.12 0.15 1,900 0.12 0.10 2,100 0.15 0.20Example 10 A B AA 1,800 0.10 0.15 1,900 0.10 0.10 2,100 0.13 0.20Example 11 A B AA 1,800 0.30 0.15 1,900 0.30 0.10 2,100 0.33 0.20Example 12 A B AA 5,000 0.70 0.70 100,000 1.00 1.50 — — — Example 13 A BAA   6 × 10⁸ 0.55 0.65 6 × 10⁸ 0.55 0.68 7 × 10⁸ 0.70 0.70 Example 14 AB AA 800 0.20 0.10 900 0.23 0.15 1,000 0.25 0.30 Comp Ex. 6 A B B 1,9001.80 0.50 3,500 2.25 1.00 10,000 2.50 1.15 Comp Ex. 7 A C B 2,200 1.050.95 4,500 1.80 1.20 12,000 1.95 1.50 Comp Ex. 8 B D B 1,900 1.25 0.953,500 1.85 1.55 10,000 1.95 1.80 Comp Ex. 9 B C B 1,900 1.15 0.80 3,5001.75 1.50 10,000 1.95 1.80 Comp Ex. 10 B C B 6,000 2.80 2.50 10⁷ or more3.50 3.40 — — — Comp Ex. 11 B C B   1 × 10⁹ 1.00 1.25 7 × 10⁸ 0.90 1.358 × 10⁸ 1.05 1.50 Comp Ex. 12 A C AA 1.1 × 10⁷ 2.35 2.10 2,500 0.55 0.353,500 0.75 0.55 ITO: tin-doped indium oxide ATO: antimony-doped tinoxide Shell(1): particle having a porous matter inside the silica shelllayer Shell(2): particle having a cavity inside the silica Shell layerPorous matter: porous particle (no shell layer)

1. A process for preparing an inorganic compound particle comprising thesteps: (a) preparing separately or as a mixture aqueous alkali solutionsof a raw material silica source and a raw material non-silica inorganiccompound source to form porous material precursor particles, (b)selectively removing at least partly non-silica inorganic compoundcontaining elements other than silicon and oxygen from the porousmaterial precursor particles to obtain a dispersion of porous materialparticles or a dispersion of precursor particles having a cavity inside;and (c) adding a hydrolyzable organic silicon compound or silicic acidsolution to the porous material particles, including the precursorparticles having a cavity inside a dispersion prepared in step (b) toform a silica shell layer around said particles.
 2. The processaccording to claim 1, wherein a protecting silica film is formed on theporous material precursor particles.